layout: restructure into src/ tests/ android/ scripts/ tools/

- extension/src/{port,platform,codepage} -> src/; native_render -> src/host
  (+ dxt, shaders/); libgr2 -> src/gr2; extension/third_party -> third_party
- extension/tests -> tests/port, libgr2/tests -> tests/gr2
- android-native -> android (build.sh, push-client.sh moved in)
- script -> scripts; tools/40250 -> tools/server; oracle -> tools/granny-oracle;
  perf tools -> tools/perf
- all build trees under build/ (native, release, android, port-gate)
- xrender:: CMake aliases -> mt::; port-map ledger impl paths rewritten

No code changes. ctest 15/15, port_gate macos+android PASS, port_map check 0 errors.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

audit/contracts/world.map-load-transition.md

@@ -87,7 +87,7 @@
 
 - `project/gamescene_test.gd`：通过，验证缺图 fallback、GameScene 装配、主角定位、world reset 和实体镜像；它不证明 40250 的 Leave/Enter 顺序。
 - `project/p9_test.gd`：通过，验证小地图、昼夜、天气和 warp signal 接收；它不创建真实 world transition。
-- `project/forest_map_render_test.gd`：这是由 `script/forest_map_render_test.sh`/客户端主循环启动的 Node 脚本，不能用 `godot --headless --script` 直接当 SceneTree 测试；本轮直接启动会被 Godot 拒绝，故不得计为通过。
+- `project/forest_map_render_test.gd`：这是由 `scripts/forest_map_render_test.sh`/客户端主循环启动的 Node 脚本，不能用 `godot --headless --script` 直接当 SceneTree 测试；本轮直接启动会被 Godot 拒绝，故不得计为通过。
 
 ## Deep audit round 2026-09-20