feat: Add home screen widget for one-click proxy toggle

[cjb2667]

Summary

• Add a 1x1 home screen widget (AppWidget) for one-click proxy on/off toggle
• Widget displays a power icon with color-coded background indicating service state:
  • Dark gray = Stopped
  • Pink (#fb7299) = Connected
  • Orange = Connecting/Stopping
• Widget runs in :bg process for instant state synchronization with the proxy service
• Supports English, Simplified Chinese, and Traditional Chinese

Changes

• New: ProxyToggleWidget.kt — AppWidgetProvider with toggle and state update logic
• New: Widget layout, drawable resources, and widget info XML
• Modified: BaseService.kt — triggers widget update on state change
• Modified: AndroidManifest.xml — registers the widget receiver
• Modified: Constants.kt — adds WIDGET_UPDATE action
• Modified: strings.xml (en, zh-CN, zh-TW) — adds widget-related strings

Test plan

• Add widget to home screen from widget picker
• Tap widget to start proxy — background should turn pink
• Tap widget again to stop proxy — background should turn dark gray
• Verify connecting/stopping states show orange background
• Test widget update after toggling from the app's main UI or quick settings tile

Made with Cursor