- add `help` target and make it the default goal (bare `make` lists targets)
- add `install-android-app`: build debug APK and install on the selected device
- device selection via SERIAL/$ANDROID_SERIAL; several devices list and stop
- document the target in android/README.md
Kotlin + Jetpack Compose client for a self-hosted instance: manual
server setup and health check, auth with Keystore-backed tokens, album
and photo browsing with SSE live updates, upload queue in WorkManager
with HEIC-to-JPEG conversion, and Room/Coil offline cache. Add an
android Makefile target and revise project.md §17.