Add Android client support and unify cross-platform builds

android/README.md

@@ -0,0 +1,27 @@
+# GoTunnel Android Host
+
+This directory contains a minimal Android Studio / Gradle project skeleton for the GoTunnel Android host app.
+
+## What is included
+
+- Foreground service shell for keeping the tunnel process alive
+- Boot receiver for auto-start on device reboot
+- Network recovery helper for reconnect/restart triggers
+- Basic configuration screen for server address and token
+- Notification channel and ongoing service notification
+- A stub bridge layer that can later be replaced with a gomobile/native Go core binding
+
+## Current status
+
+The Go tunnel core is not wired into Android yet. `GoTunnelBridge` returns a stub controller so the app structure can be developed independently from the Go runtime integration.
+
+## Open in Android Studio
+
+Open the `android/` folder as a Gradle project. Android Studio can sync it directly and generate a wrapper if you want to build from the command line later.
+
+## Notes
+
+- The foreground service is marked as `dataSync` and starts in sticky mode.
+- Auto-start is controlled by the saved configuration.
+- Network restoration currently triggers a restart hook in the stub controller.
+- Replace the stub bridge with a native binding when the Go client core is exported for Android.