Implement complete GPS speedometer functionality

Features implemented:
- Real-time GPS speed tracking with permission handling
- Customizable speed units (km/h, mph) with persistent settings
- Digital and analog speedometer display styles
- Dark/light theme support with system integration
- Optional metrics: coordinates, distance, trip time, GPS accuracy
- Trip reset functionality and error handling
- Modular architecture with Provider state management

Technical details:
- Added dependencies: geolocator, permission_handler, provider, shared_preferences
- Configured Android location permissions (FINE_LOCATION, COARSE_LOCATION)
- Portrait orientation lock for mobile-first experience
- Extensible settings system for future customization options
- Clean separation of concerns: providers, screens, widgets

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

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

android/app/src/main/AndroidManifest.xml

@@ -1,4 +1,10 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- Location permissions for GPS speedometer -->
+    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
+    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
+    <!-- Optional: for background location access -->
+    <uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
+    
     <application
         android:label="gps_speedo"
         android:name="${applicationName}"