fix: redirect to /setup/unresolved after series scan completes

- Add 'system_progress' event type to loading page redirect condition
- Add checkUnresolvedAndRedirect() for phase=initial to handle race condition
  where backend initialization completes before WebSocket connects
- Backend now emits series_sync progress events during initial setup
- Loading page checks /api/setup/unresolved immediately on load for phase=initial
- Fixes users getting stuck on loading page after setup

src/server/services/setup_service.py

@@ -267,7 +267,7 @@ class SetupService:
         )
 
     @classmethod
-    async def run(cls) -> int:
+    async def run(cls) -> tuple[int, int]:
         """Run the setup service.
         
         Scans anime folders, creates AnimeSeries records, and resolves
@@ -275,11 +275,11 @@ class SetupService:
         that initial scan hasn't been completed yet (via _check_initial_scan_status).
         
         Returns:
-            Number of new series created
+            Tuple of (number of new series created, number of unresolved folders)
         """
         if not settings.anime_directory:
             logger.info("Anime directory not configured, skipping setup")
-            return 0
+            return 0, 0
         
         anime_dir = Path(settings.anime_directory)
         if not anime_dir.is_dir():
@@ -287,7 +287,7 @@ class SetupService:
                 "Anime directory does not exist, skipping setup: %s",
                 anime_dir
             )
-            return 0
+            return 0, 0
         
         logger.info("Running setup service...")
         
@@ -385,6 +385,7 @@ class SetupService:
                             "Could not resolve series key for folder, tracking as unresolved: %s",
                             folder_name
                         )
+                        unresolved_count += 1
                         continue
                     
                     # Also check if a series with this key already exists (different folder, same anime)
@@ -445,6 +446,6 @@ class SetupService:
                 error=str(e),
                 exc_info=True
             )
-            return created_count
+            return created_count, unresolved_count
         
-        return created_count
+        return created_count, unresolved_count