Fix setup/loading flow and WebSocket connection

1. Setup redirect flow (setup -> loading -> login):
   - Add /loading to exempt paths
   - Redirect setup to login after completion
   - Redirect loading to login when initialization complete

2. Close pages after completion:
   - Block access to /setup after setup is done
   - Block access to /loading after initialization complete
   - Proper redirect handling prevents re-access

3. Fix WebSocket 403 error:
   - Change /ws/progress to /ws/connect (correct endpoint)
   - Add /ws/connect to exempt paths
   - Subscribe to 'system' room for progress updates
   - Fix message data handling format

src/server/middleware/setup_redirect.py

@@ -32,9 +32,11 @@ class SetupRedirectMiddleware(BaseHTTPMiddleware):
     # Paths that should always be accessible, even without setup
     EXEMPT_PATHS = {
         "/setup",  # Setup page itself
+        "/loading",  # Loading page (initialization progress)
         "/login",  # Login page (needs to be accessible after setup)
         "/queue",  # Queue page (for initial load)
         "/api/auth/",  # All auth endpoints (setup, login, logout, register)
+        "/ws/connect",  # WebSocket connection (needed for loading page)
         "/api/queue/",  # Queue API endpoints
         "/api/downloads/",  # Download API endpoints
         "/api/config/",  # Config API (needed for setup and management)
@@ -115,6 +117,29 @@ class SetupRedirectMiddleware(BaseHTTPMiddleware):
         """
         path = request.url.path
         
+        # Check if trying to access setup or loading page after completion
+        if path in ("/setup", "/loading"):
+            if not self._needs_setup():
+                # Setup is complete, check loading status
+                if path == "/setup":
+                    # Redirect to loading if initialization is in progress
+                    # Otherwise redirect to login
+                    return RedirectResponse(url="/login", status_code=302)
+                elif path == "/loading":
+                    # Check if initialization is complete
+                    try:
+                        from src.server.database.connection import get_db_session
+                        from src.server.database.system_settings_service import SystemSettingsService
+                        
+                        async with get_db_session() as db:
+                            is_complete = await SystemSettingsService.is_initial_scan_completed(db)
+                            if is_complete:
+                                # Initialization complete, redirect to login
+                                return RedirectResponse(url="/login", status_code=302)
+                    except Exception:
+                        # If we can't check, allow access to loading page
+                        pass
+        
         # Skip setup check for exempt paths
         if self._is_path_exempt(path):
             return await call_next(request)