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/README.md

@@ -0,0 +1,122 @@
+# Lô tô — Android
+
+![build-debug](https://github.com/tiennm99/loto-android/actions/workflows/build-debug.yml/badge.svg)
+
+Native Android port of [tiennm99/loto](https://github.com/tiennm99/loto) (SvelteKit web app).
+
+Lô tô hội chợ TN1 — Vietnamese fairground bingo with host (quản trò) + player modes,
+called-number speech in Vietnamese (Hoài My / Nam Minh voices).
+
+## Stack
+
+- Kotlin 2.1 + Jetpack Compose + Material 3
+- Single Activity, single Gradle module (`:app`)
+- Audio: AndroidX Media3 ExoPlayer (bundled MP3s in `assets/audio/`)
+- Settings persistence: DataStore Preferences
+- minSdk 24 · targetSdk 35 · JDK 17
+
+## Build
+
+### Debug APK (no signing required)
+
+```bash
+./gradlew :app:assembleDebug
+# Output: app/build/outputs/apk/debug/app-debug.apk
+```
+
+### Install on connected device/emulator
+
+```bash
+./gradlew :app:installDebug
+```
+
+### Open in Android Studio
+
+Open the repo root in Android Studio Ladybug (2024.2) or newer. The IDE picks
+up the Gradle wrapper automatically. Run the `app` configuration on any API 24+
+device or emulator.
+
+## Tests
+
+### Unit tests (JVM, no device needed)
+
+```bash
+./gradlew :app:test
+```
+
+Covers: `GameLogicTest`, `VietnameseNumberTest`, `VoiceManifestTest`,
+`SettingsRepositoryTest`, `CallBusTest`, `PlayerBoardViewModelTest`,
+`MasterPanelViewModelTest`, `MasterBoardLayoutTest`.
+
+### Instrumentation tests (requires connected device or emulator)
+
+```bash
+./gradlew :app:connectedDebugAndroidTest
+```
+
+Includes `MainActivityComposeSmokeTest` — cold-start → generate grid → assert 81 cells.
+
+## Release signing
+
+Release builds read signing credentials from environment variables so the
+keystore is never committed to the repository.
+
+```bash
+export LOTO_KEYSTORE_PATH=/path/to/loto-release.jks
+export LOTO_KEYSTORE_PASSWORD=<store-password>
+export LOTO_KEY_ALIAS=<key-alias>
+export LOTO_KEY_PASSWORD=<key-password>
+
+./gradlew :app:assembleRelease   # signed APK
+./gradlew :app:bundleRelease     # signed AAB for Play Store
+```
+
+Local convention: store the keystore at `~/.android/loto-release.jks`.
+
+### GitHub Secrets (for CI)
+
+Set the following secrets in the repository settings under **Settings → Secrets → Actions**:
+
+| Secret | Description |
+|--------|-------------|
+| `KEYSTORE_BASE64` | `base64 -w0 loto-release.jks` output |
+| `KEYSTORE_PASSWORD` | Keystore password |
+| `KEY_ALIAS` | Key alias inside the keystore |
+| `KEY_PASSWORD` | Key password |
+
+**Never commit `keystore.jks`, `.env`, or any file containing these values.**
+
+## CI / CD
+
+| Workflow | Trigger | Tasks |
+|----------|---------|-------|
+| `build-debug` | push to `main`, any PR | `lint test assembleDebug` |
+| `release` | tag `v*.*.*` | `bundleRelease assembleRelease` + sign + upload to GH Release |
+
+Tag a release:
+
+```bash
+git tag v1.0.0
+git push origin v1.0.0
+```
+
+The `release` workflow will sign and attach the APK + AAB to the GitHub Release page.
+
+## Version bump
+
+1. Increment `versionCode` and `versionName` in `app/build.gradle.kts`.
+2. Commit, tag, push tag.
+
+## App ID
+
+`com.miti99.loto` — registered in `AndroidManifest.xml` and `app/build.gradle.kts`.
+
+## Audio
+
+Bundled MP3 voice clips under `assets/audio/{hoai-my,nam-minh}/{1..90,cho,kinh}.mp3`.
+Generated from the upstream repo's `scripts/generate-audio.py` using Microsoft Edge TTS.
+Re-generate by running that script against a Python 3.10+ environment with `edge-tts` installed.
+
+## License
+
+Same license as upstream [`tiennm99/loto`](https://github.com/tiennm99/loto).