Add Jellyfin library mapping support

Add support for Jellyfin library-to-category mappings used during import. Key changes:

- UI: ImporterView now lets users fetch Jellyfin libraries, configure per-library category (TV/Anime/Movies/Music/skip) and optional path segments, and persists mappings to API settings and localStorage.
- API/types: Add jellyfin_library_mappings to ApiSettingsItem/CreateSettingsInput and UserSettings (JSON string of LibraryMapping[]), and wire conversion helpers in src/api.ts and src/types.ts.
- Jellyfin importer: Introduce LibraryMapping type, fetchJellyfinLibraries, helper functions to resolve library from ParentId or Path (extractLibraryFromPath, findLibraryForItem), and update item conversion (movies/series/albums) to apply mappings and skip items marked 'skip'. Import flow now fetches libraries to build id->name map and passes mappings through to converters.

This enables category-aware imports and allows skipping libraries during Jellyfin imports.

src/api.ts

@@ -663,6 +663,7 @@ export interface ApiSettingsItem {
   auto_play_trailers: boolean;
   language: string;
   theme: string;
+  jellyfin_library_mappings?: string; // JSON string of LibraryMapping[]
   created_at?: string;
   updated_at?: string;
 }
@@ -676,6 +677,7 @@ export interface CreateSettingsInput {
   auto_play_trailers?: boolean;
   language?: string;
   theme?: string;
+  jellyfin_library_mappings?: string;
 }
 
 export interface UpdateSettingsInput extends Partial<CreateSettingsInput> {}
@@ -691,6 +693,7 @@ export function convertApiToSettings(apiItem: ApiSettingsItem): UserSettings {
     autoPlayTrailers: apiItem.auto_play_trailers || false,
     language: apiItem.language || 'en',
     theme: (apiItem.theme as 'light' | 'dark' | 'system') || 'system',
+    jellyfinLibraryMappings: apiItem.jellyfin_library_mappings,
     createdAt: apiItem.created_at,
     updatedAt: apiItem.updated_at,
   };
@@ -706,6 +709,7 @@ export function convertSettingsToApi(settings: UserSettings): CreateSettingsInpu
     auto_play_trailers: settings.autoPlayTrailers,
     language: settings.language,
     theme: settings.theme,
+    jellyfin_library_mappings: settings.jellyfinLibraryMappings,
   };
 }