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)

src/server/web/static/js/app.js

@@ -186,9 +186,10 @@ class AniWorldApp {
             console.log('Connected to server');
             
             // Subscribe to rooms for targeted updates
-            this.socket.join('scan_progress');
-            this.socket.join('download_progress');
+            // Valid rooms: downloads, queue, scan, system, errors
+            this.socket.join('scan');
             this.socket.join('downloads');
+            this.socket.join('queue');
             
             this.showToast(this.localization.getText('connected-server'), 'success');
             this.updateConnectionStatus();

src/server/web/static/js/queue.js

@@ -32,8 +32,9 @@ class QueueManager {
             console.log('Connected to server');
             
             // Subscribe to rooms for targeted updates
+            // Valid rooms: downloads, queue, scan, system, errors
             this.socket.join('downloads');
-            this.socket.join('download_progress');
+            this.socket.join('queue');
             
             this.showToast('Connected to server', 'success');
         });