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/Media.php

@@ -64,12 +64,7 @@ class Media extends BaseModel {
             $stmt = $this->pdo->prepare($query);
             $stmt->execute($params);
             $items = $stmt->fetchAll();
-            
-            // Cast-Mitglieder für jedes Medium laden
-            foreach ($items as &$item) {
-                $item['staff'] = $this->getCastForMedia($item['id']);
-            }
-            
+
             // Count Query
             $countQuery = "SELECT COUNT(*) FROM {$this->table} WHERE 1=1";
             $countParams = [];
@@ -93,11 +88,6 @@ class Media extends BaseModel {
         } else {
             $items = $this->findAll($conditions, 'createdAt DESC', $limit, $offset);
             $total = $this->count($conditions);
-            
-            // Cast-Mitglieder für jedes Medium laden
-            foreach ($items as &$item) {
-                $item['staff'] = $this->getCastForMedia($item['id']);
-            }
         }
         
         return [