feat: build Sub2API monitor Android prototype

README.md

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+# Sub2API Monitor
+
+Android home-screen widget prototype for monitoring Sub2API usage and service status.
+
+## Current Scope
+
+- Native Android app in Kotlin.
+- Jetpack Compose configuration screen.
+- Jetpack Glance home-screen widget.
+- Local configuration with DataStore.
+- Mock Sub2API monitoring data.
+- Manual widget refresh action.
+- WorkManager refresh scheduling boundary.
+- Last successful snapshot is preserved when refresh fails.
+
+## Configuration
+
+The app lets the user enter:
+
+- Sub2API base URL.
+- Admin key.
+- Automatic refresh interval in minutes.
+
+The admin key is stored locally through DataStore and is not rendered in the widget.
+
+## Widget States
+
+- Missing configuration: shows `请先配置 Sub2API`.
+- Configured with data: shows dashboard metrics, recent calls, model TOP4, and lifetime totals.
+- Refresh failure: stores the error while keeping the last successful snapshot visible.
+
+## Replacing Mock Data
+
+The first real integration should replace `MockSub2ApiRepository` with a network-backed implementation of `Sub2ApiRepository`. Keep the widget and Compose UI consuming `Sub2ApiSnapshot` so the rendering layer does not need structural changes.
+
+## Build
+
+Open this folder in Android Studio or run:
+
+```powershell
+.\gradlew :app:assembleDebug
+```
+
+This workspace currently does not include a Gradle wrapper jar. If Android Studio is used, let it sync the Gradle project and generate/use its configured Gradle installation.