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/unit/test_provider_config_manager.py

@@ -6,7 +6,7 @@ from pathlib import Path
 
 import pytest
 
-from src.core.providers.config_manager import (
+from src.server.providers.config_manager import (
     ProviderConfigManager,
     ProviderSettings,
     get_config_manager,
@@ -407,7 +407,7 @@ class TestGetConfigManagerSingleton:
     def test_returns_instance(self):
         """get_config_manager should return a ProviderConfigManager."""
         # Reset global state for test
-        import src.core.providers.config_manager as cm
+        import src.server.providers.config_manager as cm
         cm._config_manager = None
 
         manager = get_config_manager()
@@ -418,7 +418,7 @@ class TestGetConfigManagerSingleton:
 
     def test_returns_same_instance(self):
         """get_config_manager should return same instance on repeated calls."""
-        import src.core.providers.config_manager as cm
+        import src.server.providers.config_manager as cm
         cm._config_manager = None
 
         first = get_config_manager()