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/screens/settings_screen.dart

@@ -128,6 +128,17 @@ class SettingsScreen extends StatelessWidget {
                 }
               },
             ),
+            RadioListTile<SpeedUnit>(
+              title: const Text('Knots'),
+              value: SpeedUnit.knots,
+              groupValue: settings.speedUnit,
+              onChanged: (value) {
+                if (value != null) {
+                  settings.setSpeedUnit(value);
+                  Navigator.pop(context);
+                }
+              },
+            ),
           ],
         ),
         actions: [
@@ -183,4 +194,5 @@ class SettingsScreen extends StatelessWidget {
       ),
     );
   }
+
 }