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>

tools/CMakeLists.txt

@@ -1,17 +1,17 @@
 # M0 工具。只依赖 libgr2。
 add_executable(gr2dump gr2dump/main.cpp)
-target_link_libraries(gr2dump PRIVATE xrender::libgr2)
+target_link_libraries(gr2dump PRIVATE mt::libgr2)
 
 add_executable(gr2fuzz gr2fuzz/main.cpp)
-target_link_libraries(gr2fuzz PRIVATE xrender::libgr2)
+target_link_libraries(gr2fuzz PRIVATE mt::libgr2)
 
-# M2 门禁·主：libgr2 vs oracle 逐字段对拍（读 oracle/oracle.exe 产出的 .bin）
+# M2 门禁·主：libgr2 vs oracle 逐字段对拍（读 tools/granny-oracle/oracle.exe 产出的 .bin）
 add_executable(oracle_diff oracle_diff/main.cpp)
-target_link_libraries(oracle_diff PRIVATE xrender::libgr2)
+target_link_libraries(oracle_diff PRIVATE mt::libgr2)
 
 # bisect：dump 每骨 world 3x3 的 det / shear / scale spread（查 dance_1 头塌陷）
 add_executable(anim_probe anim_probe/main.cpp)
-target_link_libraries(anim_probe PRIVATE xrender::libgr2)
+target_link_libraries(anim_probe PRIVATE mt::libgr2)
 
 
 # gr2dump --gltf 需要 tinygltf（M0 T8 辅助、可延后）：