feat: add CLI args, health endpoint, and fix torznab search

- Add clap for CLI argument parsing (-c config, -p port)
- Add health endpoint showing service status at /api/health
- Add IndexerType enum for auto URL construction (jackett/prowlarr/torznab)
- Fix Axum 0.8 route syntax ({param} instead of :param)
- Fix torznab search to use 'q' param instead of artist/album (Jackett only supports q)

config.example.yaml

@@ -1,3 +1,6 @@
+app:
+  port: 3000
+
 database:
   url: "postgresql://music:music@localhost:5433/music_aggregator"
 
@@ -6,6 +9,7 @@ metadata:
 
 indexers:
   - name: "Jackett"
+    indexer_type: jackett  # jackett, prowlarr, or torznab
     url: "http://localhost:9117"
     api_key: "your-jackett-api-key"