Fix/sonar maintainability rebased (#209)

* refactor(sonar): use override instead of redundant virtual (cpp:S3471)

* refactor(sonar): remove empty statements, one declaration per statement (cpp:S1116, cpp:S1659)

* refactor(sonar): drop redundant lambda return types (cpp:S3574)

* refactor(sonar): prefer using over typedef (cpp:S5416)

* refactor(sonar): use =default for trivial special members (cpp:S3490)

* refactor(sonar): use nullptr literal (cpp:S4962)

* refactor(sonar): remove redundant access specifiers (cpp:S3539)

* refactor(sonar): remove redundant casts (cpp:S1905)

* refactor(sonar): use std::scoped_lock instead of std::lock_guard (cpp:S5997)

* refactor(sonar): construct elements in place with emplace_back (cpp:S6003)

* refactor(sonar): make narrowing conversions explicit (cpp:S5276)

* refactor(sonar): mark unused parameters (cpp:S1172)

Unused names are commented out; parameters used only on some platforms
are marked [[maybe_unused]].

* refactor(sonar): declare non-mutating member functions const (cpp:S5817)

Virtual functions are left untouched so overrides keep matching.

* refactor(sonar): merge collapsible nested if statements (cpp:S1066)

Comments that preceded the inner if are kept above the merged statement.

* refactor(sonar): scope single-use variables in if init-statements (cpp:S6004)

* fix(sonar): give polymorphic base classes virtual destructors (cpp:S1235)

* refactor(sonar): use try_emplace for map insertion (cpp:S6030)

* refactor(sonar): use auto where the type is spelled out on the right (cpp:S5827)

* refactor(sonar): remove redundant parentheses (cpp:S1110)

* refactor(sonar): document intentionally empty functions (cpp:S1186)

* refactor(sonar): remove dead stores (cpp:S1854)

Side effects (e.g. LISTLINE++) are kept.

* refactor(sonar): remove unused variables, captures and private fields (cpp:S1481, cpp:S1068)

* refactor(sonar): use structured bindings for pair access (cpp:S6005)

* refactor(sonar): use range-based loops and ranges algorithms (cpp:S5566)

* refactor(sonar): split chained assignments (cpp:S1121)

* refactor(sonar): add default cases to switch statements (cpp:S3562)

* refactor(sonar): use std::size for array lengths (cpp:S7127)

* refactor(sonar): use std::ranges algorithms and std::erase(_if) (cpp:S6197)

* refactor(sonar): access static members through the class (cpp:S2209)

* refactor(sonar): add braces around nested if-else (cpp:S5261)

* refactor(sonar): avoid side effects inside typeid operands (cpp:S5279)

* refactor(sonar): drop top-level const from by-value return types (cpp:S5951)

* refactor(sonar): declare variables separately from their type definitions (cpp:S3646)

* refactor(sonar): declare loop counters in the for statement (cpp:S5955)

* refactor(sonar): rely on class template argument deduction (cpp:S6012)

* refactor(sonar): inherit base constructors instead of forwarding them (cpp:S5952)

* refactor(sonar): rename locals that shadow outer declarations (cpp:S1117)

Only local variables and definition parameters are renamed; shadowing
struct fields and enumerators in headers are left for a separate change.

* refactor(sonar): reduce enum qualification with using enum (cpp:S6177)

Applied only where no unqualified name in the block could be captured by
the introduced enumerators.

* refactor(sonar): mark converting constructors explicit (cpp:S1709)

sound_source and the gl::object conversion operators stay implicit; they
are relied upon by copy-list-initialisation and GL calls.

* refactor(sonar): initialise members in initialiser lists or declarations (cpp:S3230)

* refactor(sonar): make read-only local references and pointers const (cpp:S5350)

* refactor(sonar): take read-only pointer and reference parameters as const (cpp:S995)

TTrain command handlers keep their signature, it is fixed by the handler table.

* refactor(sonar): pass expensive-to-copy parameters by const reference (cpp:S1238)

Signatures declared in files touched by PR 206 (Driver.h, EU07.cpp) and
virtual overrides are left unchanged.

* refactor(sonar): use transparent comparators for string-keyed maps (cpp:S6045)

std::unordered_map instances and map types exposed in headers used by
other modules are left as they are.

* fix(sonar): do not use UI text as a printf format string (cpp:S5281)

Text lines containing '%' would otherwise be interpreted as format
specifiers by ImGui::TextColored.

* refactor(sonar): use std::bind_front for callbacks (cpp:S5995)

* refactor(sonar): drop const_cast on string literals passed to the Python C API (cpp:S859)

* refactor(sonar): take read-only string parameters as std::string_view (cpp:S6009)

The Windows messaging helpers keep std::string, they need c_str().

* refactor(sonar): make read-only global tables const (cpp:S5421)

Mutable global state (flags, timers, singletons) is left as is.

* refactor(sonar): replace single-case switch statements with if (cpp:S1301)

* refactor(sonar): format UUIDs and log timestamps with std::format (cpp:S6494, cpp:S5945)

* refactor(sonar): use std::array for local fixed-size arrays (cpp:S5945)

Arrays that are class members or part of headers are left unchanged.

* fix(sonar): test the bearing damage bit, not bit 0 (cpp:S872)

'DamageFlag & dtrain_bearing > 0' parsed as 'DamageFlag & (dtrain_bearing > 0)',
i.e. DamageFlag & 1, so bearing friction reacted to the wrong damage flag.

* refactor(sonar): assorted small fixes

- empty() instead of size() comparisons (cpp:S1155)
- member initialisers in declaration order (cpp:S3229)
- no redundant c_str() when a std::string is accepted (cpp:S7121)
- contains() on associative containers (cpp:S6171)
- const reference instead of a copying range-for (cpp:S6032)
- starts_with() for prefix checks (cpp:S6178)
- no std::move on temporaries (cpp:S5274)
- has_value() on std::optional (cpp:S7172)
- bool literals for bool members (cpp:S5820)
- inline only on the definition (cpp:S3548)
- explicit base access specifier (cpp:S5965)
- explicit element access instead of dereferencing an array (cpp:S7116)
- rely on the C++20 rewritten operator!= (cpp:S6186)

* refactor(sonar): more small fixes

- std::format instead of iostream manipulators in to_string/to_hex_str (cpp:S6495);
  output verified identical, negative hex values keep the unsigned form
- remove an empty compound statement (cpp:S108)
- drop an always-false unsigned < 0 branch (cpp:S1768)
- explicit lambda capture (cpp:S3608)
- std::make_unique (cpp:S5950)

* chore: strip stray carriage returns left in TTrain constructor comments

* fix: keep quantize() in its own value type

The S5276 change cast the result of the generic quantize<Type_>() to
unsigned int, which truncated float/double callers (shadow angle slider,
editor rotation snapping, AI speed control steps) and broke negative values.

* fix(sonar): use integer loop counters in segment sampling (cpp:S2193)

* refactor(sonar): clean up issues reported on PR 209

- remove locals left unused after the dead-store cleanup (cpp:S1481, cpp:S1854)
- unnamed unused parameter (cpp:S1172)
- single-use declarations moved into if init-statements (cpp:S6004)
- auto for casted initialisers (cpp:S5827)
- const references and pointers where nothing is modified (cpp:S5350)
- rename structured bindings shadowed by inner declarations (cpp:S1117)

network/backend/asio.cpp

@@ -37,8 +37,7 @@ void network::tcp::connection::connected()
 void network::tcp::connection::read_header()
 {
 	asio::async_read(m_socket, asio::buffer(m_header_buffer),
-	                    std::bind(&connection::handle_header, this,
-	                              std::placeholders::_1, std::placeholders::_2));
+	                    std::bind_front(&connection::handle_header, this));
 }
 
 void network::tcp::connection::handle_header(const asio::error_code &err, size_t bytes_transferred)
@@ -54,8 +53,7 @@ void network::tcp::connection::handle_header(const asio::error_code &err, size_t
 		return;
 	}
 
-	uint32_t sig = sn_utils::ld_uint32(header);
-	if (sig != NETWORK_MAGIC) {
+	if (uint32_t sig = sn_utils::ld_uint32(header); sig != NETWORK_MAGIC) {
 		disconnect();
 		return;
 	}
@@ -68,7 +66,7 @@ void network::tcp::connection::handle_header(const asio::error_code &err, size_t
 	}
 
 	asio::async_read(m_socket, asio::buffer(m_body_buffer),
-	                 std::bind(&connection::handle_data, this, std::placeholders::_1, std::placeholders::_2));
+	                 std::bind_front(&connection::handle_data, this));
 }
 
 void network::tcp::connection::handle_data(const asio::error_code &err, size_t bytes_transferred)
@@ -91,9 +89,9 @@ void network::tcp::connection::handle_data(const asio::error_code &err, size_t b
 	read_header();
 }
 
-void network::tcp::connection::write_message(const message &msg, std::ostream &stream)
+void network::tcp::connection::write_message(const message &msg, std::ostream &stream) const
 {
-	size_t beg = (size_t)stream.tellp();
+	auto beg = (size_t)stream.tellp();
 
 	sn_utils::ls_uint32(stream, NETWORK_MAGIC);
 	sn_utils::ls_uint32(stream, 0);
@@ -106,14 +104,14 @@ void network::tcp::connection::write_message(const message &msg, std::ostream &s
 		return;
 	}
 	stream.seekp(beg + 4, std::ios_base::beg);
-	sn_utils::ls_uint32(stream, size);
+	sn_utils::ls_uint32(stream, static_cast<uint32_t>(size));
 
 	stream.seekp(0, std::ios_base::end);
 }
 
 void network::tcp::connection::send_messages(const std::vector<std::shared_ptr<message> > &messages)
 {
-	if (messages.size() == 0)
+	if (messages.empty())
 		return;
 
 	std::ostringstream stream;
@@ -138,7 +136,7 @@ void network::tcp::connection::send_message(const message &msg)
 network::tcp::server::server(std::shared_ptr<std::istream> buf, asio::io_context &io_ctx, const std::string &host, uint32_t port)
     : network::server(buf), m_acceptor(io_ctx), m_io_ctx(io_ctx)
 {
-	auto endpoint = asio::ip::tcp::endpoint(asio::ip::make_address(host), port);
+	auto endpoint = asio::ip::tcp::endpoint(asio::ip::make_address(host), static_cast<asio::ip::port_type>(port));
 	m_acceptor.open(endpoint.protocol());
 	m_acceptor.set_option(asio::socket_base::reuse_address(true));
 	m_acceptor.set_option(asio::ip::tcp::no_delay(true));
@@ -150,10 +148,10 @@ network::tcp::server::server(std::shared_ptr<std::istream> buf, asio::io_context
 
 void network::tcp::server::accept_conn()
 {
-    std::shared_ptr<connection> conn = std::make_shared<connection>(m_io_ctx);
-    conn->set_handler(std::bind(&server::handle_message, this, conn, std::placeholders::_1));
+    auto conn = std::make_shared<connection>(m_io_ctx);
+    conn->set_handler(std::bind_front(&server::handle_message, this, conn));
 
-    m_acceptor.async_accept(conn->m_socket, std::bind(&server::handle_accept, this, conn, std::placeholders::_1));
+    m_acceptor.async_accept(conn->m_socket, std::bind_front(&server::handle_accept, this, conn));
 }
 
 void network::tcp::server::handle_accept(std::shared_ptr<connection> conn, const asio::error_code &err)
@@ -175,7 +173,7 @@ void network::tcp::server::handle_accept(std::shared_ptr<connection> conn, const
 // ------------------
 
 network::tcp::client::client(asio::io_context &io_ctxx, const std::string &hostarg, uint32_t portarg)
-    : host(hostarg), port(portarg), io_ctx(io_ctxx)
+    : io_ctx(io_ctxx), host(hostarg), port(portarg)
 {
 }
 
@@ -184,21 +182,21 @@ void network::tcp::client::connect()
 	if (this->conn)
 		return;
 
-	std::shared_ptr<connection> conn = std::make_shared<connection>(io_ctx, true, resume_frame_counter);
-	conn->set_handler(std::bind(&client::handle_message, this, conn, std::placeholders::_1));
+	auto newconnection = std::make_shared<connection>(io_ctx, true, resume_frame_counter);
+	newconnection->set_handler(std::bind_front(&client::handle_message, this, newconnection));
 
 	asio::ip::tcp::endpoint endpoint(
-	            asio::ip::make_address(host), port);
-	conn->m_socket.open(endpoint.protocol());
-	conn->m_socket.set_option(asio::ip::tcp::no_delay(true));
-	conn->m_socket.async_connect(endpoint,
-	                    std::bind(&client::handle_accept, this, std::placeholders::_1));
+	            asio::ip::make_address(host), static_cast<asio::ip::port_type>(port));
+	newconnection->m_socket.open(endpoint.protocol());
+	newconnection->m_socket.set_option(asio::ip::tcp::no_delay(true));
+	newconnection->m_socket.async_connect(endpoint,
+	                    std::bind_front(&client::handle_accept, this));
 
-	this->conn = conn;
+	this->conn = newconnection;
 
 }
 
-void network::tcp::client::handle_accept(const asio::error_code &err)
+void network::tcp::client::handle_accept(const asio::error_code &err) const
 {
 	if (!err)
 	{
@@ -212,7 +210,7 @@ void network::tcp::client::handle_accept(const asio::error_code &err)
 }
 
 network::tcp::asio_manager::asio_manager() {
-	backend_list().emplace("tcp", this);
+	backend_list().try_emplace("tcp", this);
 }
 
 std::shared_ptr<network::server> network::tcp::asio_manager::create_server(std::shared_ptr<std::fstream> backbuffer, const std::string &conf) {