test: add tests for scheduled folder scan and startup NFO repair removal

Add comprehensive test coverage for Tasks 1.1–1.5 and 2.1:

- test_scheduler_config_model.py: folder_scan_enabled defaults, explicit
  values, backward compatibility with old configs, serialization roundtrip
- test_folder_scan_service.py (new): prerequisites, NFO repair integration,
  folder rename integration, poster check/download, semaphore values,
  NFO thumb URL extraction, full end-to-end scan flow
- test_scheduler_service.py: scheduler _perform_rescan integration with
  folder_scan_enabled (called when enabled, skipped when disabled, error
  handling and broadcasting), folder_scan_enabled in get_status output
- test_nfo_repair_startup.py: verify perform_nfo_repair_scan is NOT called
  during FastAPI lifespan startup and IS called from FolderScanService

All 90 tests pass.

tests/unit/test_scheduler_service.py

@@ -9,16 +9,16 @@ Covers:
 - Error handling and edge cases
 """
 from datetime import datetime, timezone
-from unittest.mock import AsyncMock, MagicMock, Mock, patch, call
+from unittest.mock import AsyncMock, MagicMock, Mock, call, patch
 
 import pytest
 from apscheduler.triggers.cron import CronTrigger
 
 from src.server.models.config import AppConfig, SchedulerConfig
 from src.server.services.scheduler_service import (
+    _JOB_ID,
     SchedulerService,
     SchedulerServiceError,
-    _JOB_ID,
     get_scheduler_service,
     reset_scheduler_service,
 )
@@ -364,6 +364,7 @@ class TestGetStatus:
             schedule_time="04:00",
             schedule_days=["mon"],
             auto_download_after_rescan=True,
+            folder_scan_enabled=True,
         )
         status = scheduler_service.get_status()
 
@@ -373,13 +374,100 @@ class TestGetStatus:
         assert "schedule_time" in status
         assert "schedule_days" in status
         assert "auto_download_after_rescan" in status
+        assert "folder_scan_enabled" in status
         assert status["schedule_time"] == "04:00"
         assert status["schedule_days"] == ["mon"]
         assert status["auto_download_after_rescan"] is True
+        assert status["folder_scan_enabled"] is True
         assert status["is_running"] is False
         assert status["next_run"] is None
 
 
+# ---------------------------------------------------------------------------
+# 12.11  _perform_rescan() with folder_scan_enabled=True
+# ---------------------------------------------------------------------------
+
+class TestPerformRescanFolderScan:
+    @pytest.mark.asyncio
+    async def test_folder_scan_called_when_enabled(self, scheduler_service):
+        scheduler_service._config = SchedulerConfig(
+            folder_scan_enabled=True,
+            schedule_time="03:00",
+            schedule_days=ALL_DAYS,
+        )
+
+        mock_anime = MagicMock()
+        mock_anime.rescan = AsyncMock()
+        mock_anime._cached_list_missing.return_value = []
+
+        mock_ws = MagicMock()
+        mock_ws.manager.broadcast = AsyncMock()
+
+        mock_folder_scan = AsyncMock()
+
+        with patch("src.server.utils.dependencies.get_anime_service", return_value=mock_anime), \
+             patch("src.server.services.websocket_service.get_websocket_service", return_value=mock_ws), \
+             patch("src.server.services.folder_scan_service.FolderScanService") as MockFSS:
+            MockFSS.return_value.run_folder_scan = mock_folder_scan
+            await scheduler_service._perform_rescan()
+
+        mock_folder_scan.assert_awaited_once()
+
+    @pytest.mark.asyncio
+    async def test_folder_scan_skipped_when_disabled(self, scheduler_service):
+        scheduler_service._config = SchedulerConfig(
+            folder_scan_enabled=False,
+            schedule_time="03:00",
+            schedule_days=ALL_DAYS,
+        )
+
+        mock_anime = MagicMock()
+        mock_anime.rescan = AsyncMock()
+        mock_anime._cached_list_missing.return_value = []
+
+        mock_ws = MagicMock()
+        mock_ws.manager.broadcast = AsyncMock()
+
+        mock_folder_scan = AsyncMock()
+
+        with patch("src.server.utils.dependencies.get_anime_service", return_value=mock_anime), \
+             patch("src.server.services.websocket_service.get_websocket_service", return_value=mock_ws), \
+             patch("src.server.services.folder_scan_service.FolderScanService") as MockFSS:
+            MockFSS.return_value.run_folder_scan = mock_folder_scan
+            await scheduler_service._perform_rescan()
+
+        mock_folder_scan.assert_not_called()
+
+    @pytest.mark.asyncio
+    async def test_folder_scan_error_broadcasts_and_does_not_crash(self, scheduler_service):
+        scheduler_service._config = SchedulerConfig(
+            folder_scan_enabled=True,
+            schedule_time="03:00",
+            schedule_days=ALL_DAYS,
+        )
+
+        mock_anime = MagicMock()
+        mock_anime.rescan = AsyncMock()
+        mock_anime._cached_list_missing.return_value = []
+
+        mock_ws = MagicMock()
+        mock_ws.manager.broadcast = AsyncMock()
+
+        mock_folder_scan = AsyncMock(side_effect=RuntimeError("folder scan boom"))
+
+        with patch("src.server.utils.dependencies.get_anime_service", return_value=mock_anime), \
+             patch("src.server.services.websocket_service.get_websocket_service", return_value=mock_ws), \
+             patch("src.server.services.folder_scan_service.FolderScanService") as MockFSS:
+            MockFSS.return_value.run_folder_scan = mock_folder_scan
+            # Should NOT raise
+            await scheduler_service._perform_rescan()
+
+        mock_folder_scan.assert_awaited_once()
+        calls = [str(c) for c in mock_ws.manager.broadcast.call_args_list]
+        assert any("folder_scan_error" in c for c in calls)
+        assert scheduler_service._scan_in_progress is False
+
+
 # ---------------------------------------------------------------------------
 # Singleton helpers
 # ---------------------------------------------------------------------------