Add Jellyfin mappings and optimize cast queries

Performance and settings updates:

- Add a new jellyfin_library_mappings column to the settings table and wire it into the Settings model (update handling and default value). This enables storing Jellyfin library mappings in settings.
- Optimize Cast::list by loading all cast filmography in a single joined query and grouping results per cast to avoid N+1 queries.
- Remove per-item cast/staff loading in Media model to avoid repeated queries during list/search operations.
- Remove game-specific enrichment from MediaController search to stop extra game info lookups during search responses.

These changes reduce repeated DB calls and centralize Jellyfin mapping storage.

api/models/Settings.php

@@ -51,10 +51,14 @@ class Settings extends BaseModel {
         if (isset($data['language'])) {
             $updateData['language'] = $data['language'];
         }
-        
+
         if (isset($data['theme'])) {
             $updateData['theme'] = $data['theme'];
         }
+
+        if (isset($data['jellyfin_library_mappings'])) {
+            $updateData['jellyfin_library_mappings'] = $data['jellyfin_library_mappings'];
+        }
         
         // Check if settings row exists
         $existing = $this->findById(1);
@@ -72,7 +76,7 @@ class Settings extends BaseModel {
                 'auto_play_trailers' => 0,
                 'language' => 'en',
                 'theme' => 'system',
-                'theme' => 'system'
+                'jellyfin_library_mappings' => ''
             ];
             $mergedData = array_merge($defaultData, $updateData);
             $this->create($mergedData);