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/app/proguard-rules.pro

@@ -0,0 +1,24 @@
+# Lô tô Android — ProGuard / R8 rules
+# Default mode (not fullMode) keeps reflection-heavy Kotlin/AndroidX intact.
+
+# kotlinx.serialization — keep companion @Serializer references R8 can't infer
+-keep,includedescriptorclasses class com.miti99.loto.**$$serializer { *; }
+-keepclassmembers class com.miti99.loto.** {
+    *** Companion;
+}
+-keepclasseswithmembers class com.miti99.loto.** {
+    kotlinx.serialization.KSerializer serializer(...);
+}
+
+# Keep Kotlin metadata for runtime reflection
+-keep class kotlin.Metadata { *; }
+
+# Media3 / ExoPlayer internals — prevent stripping of codec/extractor classes
+-keep class androidx.media3.** { *; }
+-dontwarn androidx.media3.**
+
+# DataStore
+-keep class androidx.datastore.** { *; }
+
+# Compose tooling only exists in debug; suppress release warnings
+-dontwarn androidx.compose.ui.tooling.**