Add headless parallel eu7v2 scenario bake with streaming and PLCE placements

Enable --eu7v2-bake from the main binary: parallel module pool, bounded-RAM
spool flush, streaming terrain triangles, flat include/model parsing, and
eu7v2 emit/load with optional verify. Large placement .scm files emit lean
PLCE records and bake referenced .inc modules separately for reuse.

- CLI: --eu7v2-bake, --eu7v2-verify, --eu7v2-mem-limit-gb, --eu7v2-threads,
  --eu7v2-max-parse; wire max_threads through to the bake parser
- eu7v2 v2 records: PLCE placements, runtime emitter/loader, batch verify
- Parallel bake pool with session cache; drop heavy-serial parse gate in spool
  mode; parse concurrency matches thread count
- Streaming terrain: batched parallel parse+bake, scan/bake pipeline, shape
  spool with persistent buffered I/O and flush-before-read
- Parallel flat-file streaming for models/includes; pack/model spool for
  low-memory incremental flush
- Optional 50 GB private-bytes guard during headless bake

Braniewo_szeroki: 160 modules, verify PASS, ~34s bake (nmt100 ~17s vs ~190s
serial baseline).

Co-authored-by: Cursor <cursoragent@cursor.com>

scene/eu7/v2/eu7v2_emit_runtime.h

@@ -0,0 +1,99 @@
+/*
+This Source Code Form is subject to the
+terms of the Mozilla Public License, v.
+2.0. If a copy of the MPL was not
+distributed with this file, You can
+obtain one at
+http://mozilla.org/MPL/2.0/.
+*/
+
+#pragma once
+
+// ---------------------------------------------------------------------------
+// RuntimeScene -> eu7v2 emitter. Lives in the eu07_bake target because it
+// touches the parser's RuntimeModule types directly. It maps Runtime* records
+// into the same dependency-free eu7v2 structs that scene_baker uses (one
+// writer/reader per record), so the produced .eu7v2 matches what the engine
+// loads via eu7v2::load_module. For the scenario root the flattened PACK model
+// batches are deduplicated into prototypes + instances.
+// ---------------------------------------------------------------------------
+
+#include <eu07/scene/bake/module.hpp>
+#include <eu07/scene/binary/runtime_codec.hpp>
+
+#include <cstddef>
+#include <cstdint>
+#include <filesystem>
+#include <string>
+#include <vector>
+
+namespace eu07::scene::bake {
+class PackModelSpoolFile;
+class ShapeSpoolFile;
+}
+
+namespace eu7v2 {
+
+struct emit_outcome {
+    bool ok { true };
+    bool verified { false };
+    bool verify_ok { true };
+    std::string written_path;
+    std::string message;
+    std::size_t model_total { 0 };
+    std::size_t byte_size { 0 };
+    double build_ms { 0.0 };
+    double write_ms { 0.0 };
+    double verify_ms { 0.0 };
+};
+
+struct module_verify_spec {
+    std::size_t includes { 0 };
+    std::size_t placements { 0 };
+    std::size_t models { 0 };
+    std::size_t shapes { 0 };
+    std::size_t lines { 0 };
+    std::size_t tracks { 0 };
+    std::size_t traction { 0 };
+    std::size_t power { 0 };
+    std::size_t memcells { 0 };
+    std::size_t launchers { 0 };
+    std::size_t events { 0 };
+    std::size_t sounds { 0 };
+    std::size_t dynamics { 0 };
+    std::size_t trainsets { 0 };
+};
+
+// Builds the eu7v2 byte image for one baked module.
+[[nodiscard]] std::vector<std::uint8_t>
+emit_runtime_module_bytes(
+    eu07::scene::bake::RuntimeModule const &module,
+    bool is_root,
+    std::vector<eu07::scene::binary::codec::ModelSectionBatch> const *pack_batches,
+    eu07::scene::bake::PackModelSpoolFile const *pack_spool = nullptr,
+    eu07::scene::bake::ShapeSpoolFile const *shape_spool = nullptr,
+    std::filesystem::path const &text_path = {} );
+
+// Emits the module, writes "<stem>.eu7v2" next to the text source, and (when
+// verify is true) reloads the bytes and compares record counts against the
+// source RuntimeModule, filling outcome.message with a PASS/FAIL report.
+[[nodiscard]] emit_outcome
+emit_runtime_module(
+    eu07::scene::bake::RuntimeModule const &module,
+    std::filesystem::path const &text_path,
+    bool is_root,
+    std::vector<eu07::scene::binary::codec::ModelSectionBatch> const *pack_batches,
+    bool verify,
+    eu07::scene::bake::PackModelSpoolFile const *pack_spool = nullptr,
+    eu07::scene::bake::ShapeSpoolFile const *shape_spool = nullptr );
+
+// Porownanie zapisanej eu7v2 z oczekiwanymi licznikami (do odroczonego verify).
+[[nodiscard]] bool
+verify_written_module(
+    std::filesystem::path const &path,
+    module_verify_spec const &spec,
+    bool const is_root,
+    std::size_t const pack_models,
+    std::string *message_out = nullptr );
+
+} // namespace eu7v2