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>

android/app/build.gradle

@@ -0,0 +1,39 @@
+// SDLActivity shell around src/host (libmain.so). The native libraries, the SDL Java sources
+// and the assets come from ../build/android, produced by build.sh.
+plugins {
+    id 'com.android.application'
+}
+
+def nativeBuild = file("${rootDir}/../build/android")
+
+android {
+    namespace = 'org.metin2port.client'
+    compileSdk 35
+    defaultConfig {
+        applicationId 'org.metin2port.client'
+        minSdk 24
+        targetSdk 35
+        versionCode 1
+        versionName '0.1'
+        ndk { abiFilters 'arm64-v8a' }
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            signingConfig signingConfigs.debug
+        }
+    }
+    sourceSets.main {
+        java.srcDirs += "${nativeBuild}/_deps/SDL3-3.4.16/android-project/app/src/main/java"
+        jniLibs.srcDirs = ["${nativeBuild}/jniLibs"]
+        assets.srcDirs = ["${nativeBuild}/app-build/src/host/android-assets"]
+    }
+    packagingOptions {
+        jniLibs { useLegacyPackaging = true }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_17
+        targetCompatibility JavaVersion.VERSION_17
+    }
+    lint { abortOnError = false }
+}