fix: progress broadcasts now use correct WebSocket room names

- Fixed room name mismatch: ProgressService was broadcasting to
  'download_progress' but JS clients join 'downloads' room
- Added _get_room_for_progress_type() mapping function
- Updated all progress methods to use correct room names
- Added 13 new tests for room name mapping and broadcast verification
- Updated existing tests to expect correct room names
- Fixed JS clients to join valid rooms (downloads, queue, scan)

tests/integration/test_download_progress_integration.py

@@ -180,9 +180,9 @@ class TestDownloadProgressIntegration:
         connection_id = "test_client_1"
         await websocket_service.connect(mock_ws, connection_id)
         
-        # Join the queue_progress room to receive queue updates
+        # Join the queue room to receive queue updates
         await websocket_service.manager.join_room(
-            connection_id, "queue_progress"
+            connection_id, "queue"
         )
         
         # Subscribe to progress events and forward to WebSocket
@@ -254,12 +254,12 @@ class TestDownloadProgressIntegration:
         await websocket_service.connect(client1, "client1")
         await websocket_service.connect(client2, "client2")
         
-        # Join both clients to the queue_progress room
+        # Join both clients to the queue room
         await websocket_service.manager.join_room(
-            "client1", "queue_progress"
+            "client1", "queue"
         )
         await websocket_service.manager.join_room(
-            "client2", "queue_progress"
+            "client2", "queue"
         )
         
         # Subscribe to progress events and forward to WebSocket