Task 1.5: Update Provider Factory documentation for key usage

- Added comprehensive module-level docstring explaining provider vs series keys
- Enhanced Loaders class docstring with purpose and attributes documentation
- Added detailed docstring to GetLoader() method with Args/Returns/Raises sections
- Added type hints: Dict[str, Loader] for self.dict and -> None for __init__
- Clarified distinction between provider keys (e.g., 'aniworld.to') and series keys
- No functional changes - existing implementation already correct
- All 34 provider tests pass
- All 16 SeriesApp tests pass
- Updated instructions.md to mark Task 1.5 as completed
- Follows PEP 8 and PEP 257 standards

src/core/providers/provider_factory.py

@@ -1,10 +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:
 
-    def __init__(self):
-        self.dict = {"aniworld.to": AniworldLoader()}
+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]