Auto-commit after successful build: update app gameplay/UI, improve build setup, update docs/config

Changed files:\nREADME.md
app/build.gradle.kts
app/src/main/java/com/kawomi/githugandroid/GameModels.kt
app/src/main/java/com/kawomi/githugandroid/GitHugApp.kt
app/src/main/java/com/kawomi/githugandroid/GitRuntime.kt

README.md

@@ -9,7 +9,7 @@ This repository contains a starter Android app with:
 - Kotlin + Jetpack Compose project scaffolding
 - CLI-first gameplay shell
 - Optional hideable visualization panel
-- In-memory Git sandbox engine for early commands
+- A native-Git runtime scaffold with in-memory fallback while no bundled Git binary is present
 - First playable GitHug-inspired levels: `init`, `add`, and `commit`
 
 ## Product direction
@@ -75,9 +75,28 @@ It will also automatically bump the Android app version in `app/build.gradle.kts
 - incrementing `versionCode` by 1
 - incrementing the patch component of `versionName` (for example `0.1.0` → `0.1.1`)
 
+## Native Git prototype status
+
+The app now includes a **filesystem-backed runtime scaffold** for moving from the custom Kotlin Git emulator toward a real native Git backend.
+
+Current prototype behavior:
+
+- the app prepares per-level sandbox directories in app-private storage
+- terminal commands are routed through a runtime abstraction instead of directly calling the old in-memory engine
+- if a bundled native Git binary is available at runtime, Git commands are executed against a real repository sandbox
+- if no bundled native Git binary is present yet, the app automatically falls back to the existing in-memory sandbox so development can continue
+
+Planned native Git packaging path:
+
+- cross-compile Git for Android ABIs with the NDK
+- bundle one binary payload per ABI
+- extract the correct executable into app-private storage on first launch
+- keep helper shell-like commands (`ls`, `pwd`, `cat`, `touch`, `mkdir`, `rm`, `echo`) implemented in Kotlin
+
 ## Next steps toward full GitHug parity
 
-- Expand the Git sandbox to cover merge, rebase, stash, tags, remotes, reset, revert, cherry-pick, bisect, and more
+- Replace the fallback in-memory Git engine with a packaged native Git binary
+- Expand real repository-backed level validation beyond `init`, `add`, and `commit`
 - Port all original levels and hints into structured content files
 - Add richer validation rules and per-level explanations
 - Add onboarding, accessibility polish, icons, tests, and Play Store assets