Add SubscribeEvents RPC, AlbumEvent message, deprecate unary MonitorAlbum

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/claude-agent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

proto/music_agregator/v1/music_agregator.proto

@@ -3,13 +3,16 @@ package music_agregator.v1;
 option go_package = "homelab.lan/music-agregator/gen/music_agregator/v1/";
 
 service MusicAgregatorService {
-  rpc MonitorAlbum(MonitorAlbumRequest) returns (MonitorAlbumResponse) {}
+  rpc MonitorAlbum(MonitorAlbumRequest) returns (MonitorAlbumResponse) {
+    option deprecated = true;
+  }
   rpc MonitorAlbumStream(stream MonitorAlbumStreamRequest) returns (stream MonitorAlbumStreamResponse) {}
   rpc GetArtists(GetArtistsRequest) returns (GetArtistsResponse) {}
   rpc GetAlbum(GetAlbumRequest) returns (GetAlbumResponse) {}
   rpc AnalyzeAlbumRelease(AnalyzeAlbumReleaseRequest) returns (AnalyzeAlbumReleaseResponse) {}
   rpc SearchArtists(SearchArtistsRequest) returns (SearchArtistsResponse) {}
   rpc GetArtistAlbums(GetArtistAlbumsRequest) returns (GetArtistAlbumsResponse) {}
+  rpc SubscribeEvents(SubscribeEventsRequest) returns (stream AlbumEvent) {}
 }
 
 message MonitorAlbumRequest {
@@ -233,6 +236,22 @@ message AlbumLabel {
   string country = 3;
 }
 
+message SubscribeEventsRequest {
+  int64 since_seq = 1;
+}
+
+message AlbumEvent {
+  int64 seq = 1;
+  string workflow_run_id = 2;
+  string album_id = 3;
+  string quality = 4;
+  string event_type = 5;
+  string step = 6;
+  string message = 7;
+  bytes data_json = 8;
+  int64 timestamp_ms = 9;
+}
+
 enum InteractionMode {
   INTERACTION_MODE_AUTOMATIC = 0;
   INTERACTION_MODE_MANUAL = 1;