Implement v1.1 enhancements: auto-rotate, interactive gauge, and extended units

Features added:
- Auto-rotate support for portrait/landscape orientations
- Interactive gauge: tap to switch between digital and analog modes
- Extended speed units: added knots with quick selector buttons
- New SpeedUnitSelector widget for convenient unit switching

Known issues identified:
- 10 package dependencies need updates to latest compatible versions
- Orientation switching needs to override system auto-rotate toggle
- Background color customization moved back to TODO (build issues)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

lib/main.dart

@@ -14,7 +14,12 @@ class SpeedometerApp extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    SystemChrome.setPreferredOrientations([DeviceOrientation.portraitUp]);
+    SystemChrome.setPreferredOrientations([
+      DeviceOrientation.portraitUp,
+      DeviceOrientation.portraitDown,
+      DeviceOrientation.landscapeLeft,
+      DeviceOrientation.landscapeRight,
+    ]);
     
     return MultiProvider(
       providers: [