Add local Android agent activity updates

[HorusGoul]

Summary

• Adds a local-only Android Agent Activity path that reuses the existing Effect RPC shell WebSocket state instead of relay registration or FCM.
• Adds an Android foreground service in the existing t3-native-controls Expo module to keep the app process connected while backgrounded.
• Derives activity state from shell snapshots, posts local Android notifications for background approval/input/failure/completion transitions, and exposes Android settings without requiring T3 Cloud sign-in.

Refs #6

Verification

• vp check (passes with existing unrelated warnings)
• vp run typecheck
• vp test
• vp run lint:mobile (passes; ktlint/detekt not installed locally, script warns and skips them)
• APP_VARIANT=development EXPO_NO_GIT_STATUS=1 pnpm --dir apps/mobile exec expo prebuild --clean --platform android --no-install
• ./gradlew :app:assembleDebug
• ./gradlew :t3-native-controls:compileDebugKotlin

[github-actions]

Android APK preview

A self-contained Android preview APK was built for this PR.

• Artifact: t3code-preview-release-pr-9
• Size: 87.2 MiB
• SHA-256: 4f0962db52983e5dbd4d160bab8f6f1116fe60d3196ea877d9901c009f1335bb
• Source: be9f528b77c2
• Note: GitHub Actions downloads artifacts as zip archives.

Re-add the android:apk-preview label to build a fresh APK.