feat: Android support with shared mobile templates

[apotema]

Summary

Add Android build and deployment support to labelle-cli, reusing shared infrastructure from iOS implementation.

Proposed Commands

labelle android build              # Build for Android device
labelle android build --emulator   # Build for Android emulator
labelle android run --emulator     # Build and run on emulator
labelle android studio             # Generate Android Studio project

Implementation Plan

Phase 1: Shared Mobile Infrastructure

Extract common code from iOS implementation into shared modules:

• Shared mobile template (templates/mobile_main.zig)

  • Common sokol app callbacks (init, frame, event, cleanup)
  • Touch input handling (already platform-agnostic)
  • Scene loading from project's main module
  • Physics integration pattern

• Shared build helpers (mobile/build_helpers.zig)

  • Common module imports (engine, main)
  • Sokol dependency configuration
  • Framework/library linking patterns

• Shared deployment utilities (mobile/deploy.zig)

  • App bundle creation
  • Info/manifest generation
  • Binary packaging

Phase 2: Android-Specific Implementation

• Android commands (android/android_commands.zig)

  • handleAndroidBuild() - Build APK/AAB
  • handleAndroidRun() - Deploy to emulator/device
  • handleAndroidStudio() - Generate Android Studio project

• Android build.zig template

  • Target: aarch64-linux-android, x86_64-linux-android
  • NDK toolchain configuration
  • Sokol with OpenGL ES backend

• Android manifest template (AndroidManifest.xml)

  • Activity configuration for NativeActivity
  • Permissions (if needed)
  • Screen orientation settings

• Android Studio project generator

  • build.gradle templates
  • Project structure (app/, libs/)
  • Native library integration

Phase 3: Emulator/Device Deployment

• ADB integration

  • Detect connected devices/emulators
  • Install APK (adb install)
  • Launch app (adb shell am start)
  • Boot emulator if needed (emulator -avd)

• Hot reload support (stretch goal)

  • Watch for changes
  • Rebuild and reinstall

Shared vs Platform-Specific

Component	iOS	Android	Shared
Sokol callbacks	✓	✓	Yes
Touch handling	✓	✓	Yes
Scene loading	✓	✓	Yes
Physics script	✓	✓	Yes
Build.zig template	✓	✓	Partial
SDK paths	iOS SDK	NDK	No
Deployment	simctl	adb	No
Project gen	Xcode	Android Studio	No

Dependencies

• Android NDK (for cross-compilation)
• ADB (for deployment)
• Android Studio (optional, for signing/release)

Related

• iOS support: Implemented in v0.3.7
• Sokol supports Android via OpenGL ES backend

Acceptance Criteria

• labelle android build produces working APK
• labelle android run --emulator deploys and launches on emulator
• Shared template works for both iOS and Android
• Bouncing ball demo runs on Android emulator

[apotema]

Android support shipped across Phases 1–3 (closed issues #133, #134, #135, #136, #138). Phase 4 (Android Studio project generation) tracked separately in #137 and explicitly deferred as lower priority — ADB deployment works without it.

Closing the epic umbrella.