engine: add exact Windows GDI glyph backend

docs/platform-portability.md

@@ -33,7 +33,7 @@ or replaced before claiming portable exports.
 | AGE movie decode (`0x236` scene movies; `0x20f` modal LOGO/OP/ED; `0x24d` movie masks) | `FfmpegMovieDecoder` is the sole factory over the project-owned `native/age_movie_ffmpeg` ABI | Windows-x64 passes the complete 213-payload installed video/audio corpus gate plus audible LOGO/OP/CHAPTER playback and real TEST.AGF green-mask decode | Add target-specific native builds and export packaging |
 | Movie integration | Each surface owns a unique playback-instance id; `MovieRuntime` owns `IMovieDecoder` from an injected factory; video-only streams use monotonic pacing while audio-bearing streams use the Godot output clock. Opcode `0x24d` redirects decoded green bytes through the platform-neutral retained rasterizer and exact managed packed-alpha mask helper | Concurrent/restarted uses of one asset have independent frame/audio/completion/teardown state. Ordinary and mask movies share VFS/FFmpeg ownership; the mask result is a backend-neutral dynamic RGBA surface consumed by either Godot renderer. Managed code is no longer Windows-annotated, while only the win-x64 native bundle exists today | Add Linux/macOS native builds and smoke gates |
 | Movie audio | ABI v2 returns timestamped stereo float PCM; bounded managed buffering feeds a per-playback Godot `AudioStreamGenerator` and routes native movie flags to engine buses | All 29 installed audio-bearing streams decode with signal; synchronized LOGO/OP/CHAPTER playback is audibly accepted | Treat absent, distorted, or unsynchronized audio from an audio-bearing movie as a runtime bug |
-| ADV font discovery/raster fidelity | Live presentation still uses `godot/Main.cs` to load Windows `ＭＳ 明朝`/`ＭＳ ゴシック` when available and otherwise choose the existing Japanese-font/default fallback; its `Label` path substitutes FreeType embolden and a Godot outline. The new `Age.Engine.Text` core is OS-neutral: requests select native-CP932 or portable-Unicode policy, mask results normalize to 0..16 coverage/GDI-style metrics, and managed code owns deterministic compositing/layout plus bounded caches | Visible behavior is unchanged. On the reference Windows install, regular advances and SC0000 placement agree, but provisional bold remains visibly lighter/softer. Synthetic masks now test the common compositor independently of any OS font; no authored runtime code calls GDI | Next add the independent Windows GDI adapter outside `Age.Engine`, then integrate immediate surface pixels. Keep explicit portable face substitution/raster policy and do not claim cross-backend pixel equivalence |
+| ADV font discovery/raster fidelity | Live presentation still uses `godot/Main.cs` to load Windows `ＭＳ 明朝`/`ＭＳ ゴシック` when available and otherwise choose the existing Japanese-font/default fallback; its `Label` path substitutes FreeType embolden and a Godot outline. `Age.Engine.Text` remains OS-neutral. The separate optional `Age.Engine.Text.Windows` reference library now owns the authored GDI calls: `CreateICA`, bounded `CreateFontIndirectA` handles, `GetTextExtentPoint32A`, and `GetGlyphOutlineA(GGO_GRAY4_BITMAP)` | Visible behavior is unchanged because the reference backend is not wired into Godot. It explicitly requires Windows ACP 932 and reports unavailable elsewhere. Three Mincho/Gothic regular/bold samples byte-match an independent Unicode GDI oracle; synthetic masks continue to test the common compositor on every platform | Integrate immediate surface pixels against this exact Windows reference, then add an explicitly non-identical portable backend/face-substitution policy. Keep the GDI project optional and out of non-Windows deliverables rather than hiding failed exact selection |
 | Filesystem semantics | Several filename and containment comparisons use `OrdinalIgnoreCase`; installed assets are conventionally uppercase | Needs validation on case-sensitive filesystems; may hide casing or containment mistakes | Add Linux/macOS tests with mixed-case synthetic roots and use filesystem-appropriate containment rules |
 | Save/profile/settings storage | `Sys4PersistencePaths` models AGE's independent `SAVEPATH` and `REGFILEPATH` resolutions. Godot replaces Himegari's related profile directory with `user://`, yielding `user://SAVE` for native S3SD/S4SD/S3RT files and thumbnails plus `user://SYS4REG.INI` for the BOM-less CP932 options file; the preserving writer changes only its nine `[sound]` keys | Save payloads and engine options are isolated together without changing either native format. Native/drop-in resolution remains available through `USEAPPDATAFOLDER` plus both SYS4INI paths. A single-root override is rejected when `SAVEPATH` is not beneath `REGFILEPATH`, preventing cross-profile guesses | Expose explicit profile/native selection through the future launcher and allow independent overrides for profiles whose two native paths are unrelated. Validate CP932 availability, replace/flush, case, permissions, and interrupted-write behavior on each export target |
 | Game-install and repository discovery | `GameRootSelection` accepts `--game-root`, then probes the executable directory and current working directory for `SYS4INI.BIN`; on Unix the frontend prefers inherited shell `PWD` because Godot may change the process directory during project startup. Godot injects the selected root into its catalog and loose-first ALF store. `Paths.cs` remains the development/test locator for generated opcode data, diagnostics, and CLI conveniences | Installed game data no longer depends on the workspace sibling layout, enabling an executable beside `AGE.EXE`, a terminal launch from the install, or a launcher-supplied absolute profile root. A packaged export still needs its generated runtime metadata bundled independently of repository discovery | Add export packaging for the opcode/profile artifacts, let the future profile launcher pass `--game-root`, and run executable-directory/CWD plus case/permission smoke gates on Linux and macOS |