Refactor: Replace CallbackManager with Events pattern

- Replace callback system with events library in SerieScanner
- Update SeriesApp to subscribe to loader and scanner events
- Refactor ScanService to use Events instead of CallbackManager
- Remove CallbackManager imports and callback classes
- Add safe event calling with error handling in SerieScanner
- Update AniworldLoader to use Events for download progress
- Remove progress_callback parameter from download methods
- Update all affected tests for Events pattern
- Fix test_series_app.py for new event subscription model
- Comment out obsolete callback tests in test_scan_service.py

All core tests passing. Events provide cleaner event-driven architecture.

src/core/providers/base_provider.py

@@ -1,20 +1,20 @@
 from abc import ABC, abstractmethod
-from typing import Any, Callable, Dict, List, Optional
+from typing import Any, Dict, List
 
 
 class Loader(ABC):
     """Abstract base class for anime data loaders/providers."""
     @abstractmethod
-    def subscribe_download_progress(self, handler):
-        """Subscribe a handler to the download_progress event.
-        Args:
-            handler: Callable to be called with progress dict.
+    def subscribe_download_progress(self, handler):
+        """Subscribe a handler to the download_progress event.
+        Args:
+            handler: Callable to be called with progress dict.
         """
     @abstractmethod
-    def unsubscribe_download_progress(self, handler):
-        """Unsubscribe a handler from the download_progress event.
-        Args:
-            handler: Callable previously subscribed.
+    def unsubscribe_download_progress(self, handler):
+        """Unsubscribe a handler from the download_progress event.
+        Args:
+            handler: Callable previously subscribed.
         """
 
     @abstractmethod
@@ -56,8 +56,7 @@ class Loader(ABC):
         season: int,
         episode: int,
         key: str,
-        language: str = "German Dub",
-        progress_callback: Optional[Callable[[str, Dict], None]] = None,
+        language: str = "German Dub"
     ) -> bool:
         """Download episode to specified directory.
 
@@ -68,8 +67,6 @@ class Loader(ABC):
             episode: Episode number within season
             key: Unique series identifier/key
             language: Language version to download (default: German Dub)
-            progress_callback: Optional callback for progress updates
-                               called with (event_type: str, data: Dict)
 
         Returns:
             True if download successful, False otherwise