Fix rating display showing 0.7 instead of 7.0

Fixes #7

- Changed rating field type from int to double in PlexMetadata model
- Removed incorrect division by 10 in discover screen rating display
- Regenerated JSON serialization to properly parse rating as double
- Rating now displays correctly (e.g., 7.0 instead of 0.7)

lib/models/plex_metadata.dart

@@ -12,7 +12,7 @@ class PlexMetadata {
   final String title;
   final String? contentRating;
   final String? summary;
-  final int? rating;
+  final double? rating;
   final int? year;
   final String? thumb;
   final String? art;