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

tests/integration/test_nfo_repair_startup.py

@@ -34,7 +34,7 @@ class TestNfoRepairScanCalledInFolderScan:
         """folder_scan_service.py imports perform_nfo_repair_scan."""
         import importlib
 
-        source = importlib.util.find_spec("src.server.services.folder_scan_service").origin
+        source = importlib.util.find_spec("src.server.services.scheduler.folder_scan_service").origin
         with open(source, "r", encoding="utf-8") as fh:
             content = fh.read()
 
@@ -46,7 +46,7 @@ class TestNfoRepairScanCalledInFolderScan:
         """perform_nfo_repair_scan must be called inside run_folder_scan."""
         import importlib
 
-        source = importlib.util.find_spec("src.server.services.folder_scan_service").origin
+        source = importlib.util.find_spec("src.server.services.scheduler.folder_scan_service").origin
         with open(source, "r", encoding="utf-8") as fh:
             content = fh.read()
 
@@ -67,7 +67,9 @@ class TestNfoRepairScanIntegrationWithBackgroundLoader:
     @pytest.mark.asyncio
     async def test_incomplete_nfo_series_scheduled_for_repair(self, tmp_path):
         """Series whose tvshow.nfo is missing required tags are scheduled via asyncio.create_task."""
-        from src.server.services.folder_scan_service import perform_nfo_repair_scan
+        from src.server.services.scheduler.folder_scan_service import (
+            perform_nfo_repair_scan,
+        )
 
         series_dir = tmp_path / "IncompleteAnime"
         series_dir.mkdir()
@@ -83,7 +85,7 @@ class TestNfoRepairScanIntegrationWithBackgroundLoader:
         mock_repair_service.repair_series = AsyncMock(return_value=True)
 
         with patch(
-            "src.server.services.folder_scan_service._settings", mock_settings
+            "src.server.services.scheduler.folder_scan_service._settings", mock_settings
         ), patch(
             "src.core.services.nfo_repair_service.nfo_needs_repair",
             return_value=True,
@@ -103,7 +105,9 @@ class TestNfoRepairScanIntegrationWithBackgroundLoader:
     @pytest.mark.asyncio
     async def test_complete_nfo_series_not_scheduled(self, tmp_path):
         """Series whose tvshow.nfo has all required tags are not scheduled for repair."""
-        from src.server.services.folder_scan_service import perform_nfo_repair_scan
+        from src.server.services.scheduler.folder_scan_service import (
+            perform_nfo_repair_scan,
+        )
 
         series_dir = tmp_path / "CompleteAnime"
         series_dir.mkdir()
@@ -116,7 +120,7 @@ class TestNfoRepairScanIntegrationWithBackgroundLoader:
         mock_settings.anime_directory = str(tmp_path)
 
         with patch(
-            "src.server.services.folder_scan_service._settings", mock_settings
+            "src.server.services.scheduler.folder_scan_service._settings", mock_settings
         ), patch(
             "src.core.services.nfo_repair_service.nfo_needs_repair",
             return_value=False,