feat: initial Android port of tiennm99/loto

Native Android port of the SvelteKit Lô tô hội chợ Tân Tân web app.

Stack:
- Kotlin 2.1 + Jetpack Compose + Material 3
- Single Activity, single Gradle module (:app)
- Audio: AndroidX Media3 ExoPlayer with bundled MP3 voice clips
- Settings: DataStore Preferences with legacy masterMode migration
- minSdk 24, targetSdk 35, JDK 17

Game logic:
- 9x9 player card with exactly 5 numbers per row AND per column
- Soft constraint: no 3 consecutive filled columns (rejection-sampled)
- 11x9 ones-digit-aligned master tracking board
- Bingo / Cho ("waiting") state machine ported from PlayerBoard.svelte
- Forward-only auto-tick from MasterPanel via app-scoped CallBus

Audio:
- 184 MP3s pre-generated with Microsoft Edge TTS (Hoai My, Nam Minh)
- ExoPlayer playlist for cho + N gapless sequence
- Token-based cancellation matching the web voice.js semantics

CI:
- build-debug.yml: lint + test + assembleDebug on push/PR
- release.yml: signed AAB+APK on v* tag, env-driven keystore

android/.github/workflows/build-debug.yml

@@ -0,0 +1,32 @@
+name: build-debug
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '17'
+
+      - name: Set up Gradle
+        uses: gradle/actions/setup-gradle@v3
+
+      - name: Lint + unit tests + assemble debug
+        run: ./gradlew lint test :app:assembleDebug
+
+      - name: Upload debug APK
+        uses: actions/upload-artifact@v4
+        with:
+          name: debug-apk
+          path: app/build/outputs/apk/debug/*.apk
+          retention-days: 7

android/.github/workflows/release.yml

@@ -0,0 +1,39 @@
+name: release
+
+on:
+  push:
+    tags: ['v*.*.*']
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '17'
+
+      - name: Set up Gradle
+        uses: gradle/actions/setup-gradle@v3
+
+      - name: Decode keystore
+        run: echo "${{ secrets.KEYSTORE_BASE64 }}" | base64 -d > keystore.jks
+
+      - name: Build release bundle and APK
+        run: ./gradlew :app:bundleRelease :app:assembleRelease
+        env:
+          LOTO_KEYSTORE_PATH: ${{ github.workspace }}/keystore.jks
+          LOTO_KEYSTORE_PASSWORD: ${{ secrets.KEYSTORE_PASSWORD }}
+          LOTO_KEY_ALIAS: ${{ secrets.KEY_ALIAS }}
+          LOTO_KEY_PASSWORD: ${{ secrets.KEY_PASSWORD }}
+
+      - name: Upload to GitHub Release
+        uses: softprops/action-gh-release@v2
+        with:
+          files: |
+            app/build/outputs/apk/release/*.apk
+            app/build/outputs/bundle/release/*.aab