refactor: extract user_config_path() helper

Consolidates platform-specific config-directory logic (APPDATA on Windows,
~/Library/Application Support on macOS, ~/.config on Linux) into a single
user_config_path(filename) function in utilities/utilities.{cpp,h}, removing
copy-pasted #ifdef blocks from application.cpp, editor/editorSettings.cpp,
input/{keyboard,gamepad,drivermouse,uart}input.cpp.

utilities/uart.cpp

@@ -6,6 +6,7 @@
 #include "vehicle/Train.h"
 #include "utilities/parser.h"
 #include "utilities/Logs.h"
+#include "utilities/utilities.h"
 #include "simulation/simulationtime.h"
 #include "application/application.h"
 
@@ -194,21 +195,9 @@ uart_input::recall_bindings() {
     m_inputbindings.clear();
 	std::string filePath = "eu07_input-uart.ini";
 
-#ifdef _WIN32
-	if (const char *appdata = std::getenv("APPDATA"))
-	{
-		fs::path appPath = fs::path(appdata) / "MaSzyna" / "eu07_input-uart.ini";
-		if (fs::exists(appPath))
-			filePath = appPath.string();
-	}
-#else
-	if (const char *home = std::getenv("HOME"))
-	{
-		fs::path appPath = fs::path(home) / ".config" / "MaSzyna" / "eu07_input-uart.ini";
-		if (fs::exists(appPath))
-			filePath = appPath.string();
-	}
-#endif
+	fs::path appPath = user_config_path("eu07_input-uart.ini");
+	if (!appPath.empty() && fs::exists(appPath))
+		filePath = appPath.string();
 	cParser bindingparser(filePath.c_str(), cParser::buffer_FILE);
 	if (false == bindingparser.ok())
 	{

utilities/utilities.cpp

@@ -55,6 +55,22 @@ std::string Now()
 #endif
 }
 
+std::filesystem::path user_config_path(const std::string &filename)
+{
+	namespace fs = std::filesystem;
+#if defined(_WIN32)
+	if (const char *appdata = std::getenv("APPDATA"))
+		return fs::path(appdata) / "MaSzyna" / filename;
+#elif defined(__APPLE__)
+	if (const char *home = std::getenv("HOME"))
+		return fs::path(home) / "Library" / "Application Support" / "MaSzyna" / filename;
+#else
+	if (const char *home = std::getenv("HOME"))
+		return fs::path(home) / ".config" / "MaSzyna" / filename;
+#endif
+	return {}; // env var missing → caller falls back to CWD-relative filename
+}
+
 // zwraca różnicę czasu
 // jeśli pierwsza jest aktualna, a druga rozkładowa, to ujemna oznacza opóżnienie
 // na dłuższą metę trzeba uwzględnić datę, jakby opóżnienia miały przekraczać 12h (towarowych)

utilities/utilities.h

@@ -25,6 +25,10 @@ template <typename T> constexpr T sq(T v)
 	return v * v;
 }
 
+// returns the per-user config path for `filename` (platform-specific dir),
+// or an empty path if the home/appdata env var is unavailable
+std::filesystem::path user_config_path(const std::string &filename);
+
 // TODO: Shouldn't this be in globals?
 namespace paths
 {