refactor: restructure core→server, split large entity files into database module

- Move src/core/ → src/server/
- Split SerieList.py (531 lines) and series.py (414 lines) into src/server/database/
- Add database/models.py for SQLAlchemy models
- Update all test imports to reflect new structure
- Remove deprecated test files (test_serie_class.py, test_serie_folder_with_year.py)

tests/performance/test_nfo_batch_performance.py

@@ -12,7 +12,7 @@ from unittest.mock import AsyncMock, Mock, patch
 
 import pytest
 
-from src.core.services.nfo_service import NFOService
+from src.server.services.nfo_service import NFOService
 from src.server.api.nfo import batch_create_nfo
 from src.server.models.nfo import NFOBatchCreateRequest
 
@@ -297,7 +297,7 @@ class TestTMDBAPIBatchingOptimization:
             
             # Simulate rate limit on 5th call
             if call_count == 5:
-                from src.core.services.tmdb_client import TMDBAPIError
+                from src.server.services_nfo_temp.tmdb_client import TMDBAPIError
                 raise TMDBAPIError("Rate limit exceeded")
             
             await asyncio.sleep(0.01)