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/combat.death-exp-drop.md

@@ -85,7 +85,7 @@
 
 ## Regression evidence
 
-- `extension/tests/net_state_queue_test`：`POINT_EXP.amount` 累计和一次性消费、死亡状态和网络状态队列。
+- `tests/port/net_state_queue_test`：`POINT_EXP.amount` 累计和一次性消费、死亡状态和网络状态队列。
 - `project/mob_death_drop_test.gd`：怪物死亡目标/HP/名字/影子清理、掉落坐标贴地、owner/拾取/删除。
 - `project/combat_parity_test.gd`：防御球、击退阻挡、攻击锁、伤害表现和死亡抗击退相关分支。
 - `project/playable_combat_test.gd`：无目标、超距、死亡目标/自身、冷却和断线时不发送错误战斗请求。