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/port-map/EterBase/Debug.cpp.json

@@ -39,7 +39,7 @@
   },
   "LogBoxf": {
    "impl": [
-    "extension/src/platform/EterBase/Debug.cpp:LogBoxf"
+    "src/platform/EterBase/Debug.cpp:LogBoxf"
    ],
    "status": "ADAPTED",
    "note": "verbatim apart from two PORT fixes the 40250 build did not need: va_end (40250 leaks the va_list) and terminating szBuf, which _vsnprintf does not do on truncation.",
@@ -47,10 +47,10 @@
   },
   "LogBox": {
    "impl": [
-    "extension/src/platform/EterBase/Debug.cpp:LogBox"
+    "src/platform/EterBase/Debug.cpp:LogBox"
    ],
    "status": "ADAPTED",
-   "note": "40250 pops a MessageBox on g_PopupHwnd and Tracen()s the text. No window here: the text goes to stderr and is kept in LastLogBoxMessage() (extension/src/platform/EterBase/LogBox.h), because ScriptLib/PythonLauncher.cpp Traceback() reports every failed script line through LogBoxf after PyErr_Fetch has already cleared the exception — this is the only place a traceback survives.",
+   "note": "40250 pops a MessageBox on g_PopupHwnd and Tracen()s the text. No window here: the text goes to stderr and is kept in LastLogBoxMessage() (src/platform/EterBase/LogBox.h), because ScriptLib/PythonLauncher.cpp Traceback() reports every failed script line through LogBoxf after PyErr_Fetch has already cleared the exception — this is the only place a traceback survives.",
    "test": "project/python_host_check.gd — system.py's ImportError reaches GDScript through it"
   },
   "LogFile": {