refactor(scheduler): separate scheduler logic from scan/rescan logic

- Extract rescan logic into new RescanService (src/server/services/rescan_service.py)
- SchedulerService now only handles APScheduler cron scheduling
- Move scheduler sub-services (folder_rename, folder_scan, key_resolution) to scheduler/ folder
- Keep RescanOrchestrator as backward-compatible alias
- Update all imports across api/, server/, and test files

src/server/api/anime.py

@@ -20,7 +20,9 @@ from src.server.exceptions import (
 from src.server.models.anime import AnimeMetadataUpdate
 from src.server.services.anime_service import AnimeService, AnimeServiceError
 from src.server.services.background_loader_service import BackgroundLoaderService
-from src.server.services.folder_rename_service import _scan_for_pre_existing_duplicates
+from src.server.services.scheduler.folder_rename_service import (
+    _scan_for_pre_existing_duplicates,
+)
 from src.server.utils.dependencies import (
     get_anime_service,
     get_background_loader_service,

src/server/api/auth.py

@@ -165,7 +165,7 @@ async def setup_auth(req: SetupRequest):
                 
                 # Start scheduler if anime_directory is now set
                 try:
-                    from src.server.services.scheduler_service import (
+                    from src.server.services.scheduler.scheduler_service import (
                         get_scheduler_service,
                     )
 

src/server/api/config.py

@@ -57,7 +57,7 @@ async def update_config(
         # Start scheduler if anime_directory was just configured
         if anime_dir_changed:
             try:
-                from src.server.services.scheduler_service import (
+                from src.server.services.scheduler.scheduler_service import (
                     get_scheduler_service,
                 )
 

src/server/api/health.py

@@ -195,7 +195,9 @@ async def basic_health_check(request: Request) -> HealthStatus:
     # Get scheduler status for health monitoring
     scheduler_status: dict = {}
     try:
-        from src.server.services.scheduler_service import get_scheduler_service
+        from src.server.services.scheduler.scheduler_service import (
+            get_scheduler_service,
+        )
         scheduler_status = get_scheduler_service().get_status()
     except Exception:
         pass

src/server/api/scheduler.py

@@ -10,7 +10,7 @@ from fastapi import APIRouter, Depends, HTTPException, status
 
 from src.server.models.config import SchedulerConfig
 from src.server.services.config_service import ConfigServiceError, get_config_service
-from src.server.services.scheduler_service import get_scheduler_service
+from src.server.services.scheduler.scheduler_service import get_scheduler_service
 from src.server.utils.dependencies import require_auth
 
 logger = logging.getLogger(__name__)