Fix Jellyfin auth: use MediaBrowser Authorization scheme, not X-Emby-Token

This server (Jellyfin 12.0.0) rejects X-Emby-Token, X-MediaBrowser-Token,
a raw Authorization value, and Authorization: Bearer <token> - all with
401 - even against a freshly generated API key confirmed valid via curl.
Its OpenAPI spec names Authorization as the apiKey header, but the only
value it actually accepts is the legacy 'MediaBrowser Token="<key>"'
scheme, confirmed working via curl against the live server.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/main/java/com/recommendarr/service/JellyfinClient.java

@@ -16,8 +16,11 @@ public class JellyfinClient {
     }
 
     private RestClient client(IntegrationSetting setting) {
+        // This server's OpenAPI spec declares "Authorization" as a plain
+        // apiKey header, but in practice it only accepts the legacy
+        // MediaBrowser scheme value, not a raw token or Bearer prefix.
         return restClientBuilder.baseUrl(setting.getBaseUrl())
-                .defaultHeader("X-Emby-Token", setting.getApiKey())
+                .defaultHeader("Authorization", "MediaBrowser Token=\"" + setting.getApiKey() + "\"")
                 .build();
     }