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/network.error-timeout-server-state.md

@@ -66,7 +66,7 @@
 
 - `godot --headless --path project --script channel_status_test.gd`：PASS。
 - `MT_PROTOCOL=classic godot --headless --path project --script channel_status_test.gd`：PASS，覆盖 40250 classic 的 206 请求和 210 响应夹具。
-- 认证 loopback 成功路径、密码清除、挂起连接 deadline 已在 `extension/tests/net_loopback_test.cpp` 覆盖；classic transport 的同等 deadline/可写门禁在 `extension/tests/net_classic_stream_test.cpp` 覆盖。
+- 认证 loopback 成功路径、密码清除、挂起连接 deadline 已在 `tests/port/net_loopback_test.cpp` 覆盖；classic transport 的同等 deadline/可写门禁在 `tests/port/net_classic_stream_test.cpp` 覆盖。
 - 当前合同继续 `PARTIAL`：通过的状态包解析测试不能替代 40250 的认证失败、远端关闭、失败通知顺序、count 边界和完整恢复链证据。
 
 ## Active UserInterface server-state checker review