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)

src/server/providers/provider_factory.py

@@ -0,0 +1,56 @@
+"""Provider factory for managing anime content providers.
+
+This module provides a factory class for accessing different anime content
+providers (loaders). The factory uses provider identifiers (keys) to return
+the appropriate provider instance.
+
+Note: The 'key' parameter in this factory refers to the provider identifier
+(e.g., 'aniworld.to'), not to be confused with series keys used within
+providers to identify specific anime series.
+"""
+
+from typing import Dict
+
+from .aniworld_provider import AniworldLoader
+from .base_provider import Loader
+
+
+class Loaders:
+    """Factory class for managing and retrieving anime content providers.
+
+    This factory maintains a registry of available providers and provides
+    access to them via provider keys. Each provider implements the Loader
+    interface for searching and downloading anime content.
+
+    Attributes:
+        dict: Dictionary mapping provider keys to provider instances.
+              Provider keys are site identifiers (e.g., 'aniworld.to').
+    """
+
+    def __init__(self) -> None:
+        """Initialize the provider factory with available providers.
+
+        Currently supports:
+        - 'aniworld.to': AniworldLoader for aniworld.to content
+        """
+        self.dict: Dict[str, Loader] = {"aniworld.to": AniworldLoader()}
+
+    def GetLoader(self, key: str) -> Loader:
+        """Retrieve a provider instance by its provider key.
+
+        Args:
+            key: Provider identifier (e.g., 'aniworld.to').
+                 This is the site/provider key, not a series key.
+
+        Returns:
+            Loader instance for the specified provider.
+
+        Raises:
+            KeyError: If the provider key is not found in the registry.
+
+        Note:
+            The 'key' parameter here identifies the provider/site, while
+            series-specific operations on the returned Loader use series
+            keys to identify individual anime series.
+        """
+        return self.dict[key]