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>

.gitignore

@@ -2,16 +2,8 @@
 
 # build
 /build/
-/build-ios/
-/build-android/
-/build-classic/
-/build-port-gate/
-/build-debug/
-/build-asan/
+/build-*/
 /cmake-build-*/
-/build-release/
-/build-native-render/
-/build-native/
 compile_commands.json
 
 
@@ -33,21 +25,17 @@ __pycache__/
 /.cache/
 
 # oracle: cross-compiled exe + leaked Granny DLL (size / RAD IP — never commit;
-# oracle/build-wine.sh rebuilds). See oracle/README.md.
-/oracle/oracle.exe
-/oracle/*.dll
-/oracle/*.dylib
-
-# vendored-lib test artifacts
-/build-tools/
+# tools/granny-oracle/build-wine.sh rebuilds). See tools/granny-oracle/README.md.
+/tools/granny-oracle/oracle.exe
+/tools/granny-oracle/*.dll
+/tools/granny-oracle/*.dylib
 
 
 # Written by 40250 uitaskbar.py at runtime.
 /mouse.cfg
 
-# native Android client (./build-android-native.sh): SDL3 download, NDK builds, Gradle output
-/build-android-native/
-/android-native/.gradle/
-/android-native/app/build/
-/android-native/build/
-/android-native/local.properties
+# native Android client (./android/build.sh): SDL3 download, NDK builds, Gradle output
+/android/.gradle/
+/android/app/build/
+/android/build/
+/android/local.properties