Add source field, UI filter, and import mapping

Introduce a 'source' property across types and API models, include it in convertApiToMedia, and add a Source input to AddMediaView. Add source-based filtering in BrowseView (dropdown + tag icon) and ensure Clear Filters resets source. Update playnite, stashapp, and xbvr importers to set source conditionally using a new SOURCE_CATEGORY_MAPPING constant (added to types) so sources are only applied for appropriate media categories.

src/types.ts

@@ -109,3 +109,11 @@ export interface UserSettings {
   createdAt?: string;
   updatedAt?: string;
 }
+
+// Source to Category mapping - ensures sources are only used with appropriate categories
+export const SOURCE_CATEGORY_MAPPING: Record<string, MediaCategory[]> = {
+  'xbvr': ['Adult'],
+  'stashapp': ['Adult'],
+  'playnite': ['Games'],
+  'manual': ['Anime', 'Movies', 'TV Series', 'Music', 'Books', 'Adult', 'Consoles', 'Games'],
+};