feat(android): add Capacitor setup for Android APK builds

- Migrate web assets from root to www/ directory
- Add Android native project with Capacitor 8
- Add GitHub Actions workflow for automated APK builds
- Configure app identity and splash screens

.github/workflows/build-apk.yml

@@ -0,0 +1,46 @@
+name: Build Android APK
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+
+      - name: Setup Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '17'
+
+      - name: Setup Android SDK
+        uses: android-actions/setup-android@v3
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Sync Capacitor
+        run: npx cap sync android
+
+      - name: Build APK
+        working-directory: android
+        run: ./gradlew assembleDebug
+
+      - name: Upload APK
+        uses: actions/upload-artifact@v4
+        with:
+          name: impostor-game-debug
+          path: android/app/build/outputs/apk/debug/app-debug.apk
+          retention-days: 30