Refactor YouTube Playlist Downloader

- Moved main execution logic to cli.py and updated imports accordingly.
- Created a new __init__.py file to export the main function from the cli module.
- Implemented the PlaylistDownloader class in downloader.py to handle playlist downloading logic.
- Added ConfigLoader class in config.py to manage configuration settings.
- Introduced PlaylistManager class in manager.py to manage multiple playlists.
- Updated encoding handling for Windows in the main execution block.
- Removed redundant code and improved overall structure for better readability and maintainability.

ytplaylist/manager.py

@@ -0,0 +1,22 @@
+import time
+
+from .downloader import PlaylistDownloader
+
+
+class PlaylistManager:
+    def __init__(self, config):
+        self.config = config
+        self.playlists = [PlaylistDownloader(config, pl, idx) for idx, pl in enumerate(config.playlists)]
+
+    def run(self):
+        total_connections = self.config.max_parallel_downloads * self.config.aria2c_connections
+        if total_connections > 100:
+            print(
+                "\033[91m"
+                f"⚠[WARNING] Total connections ({self.config.max_parallel_downloads} × {self.config.aria2c_connections} = {total_connections}) may overload your network! Pausing 5 seconds..."
+                "\033[0m"
+            )
+            time.sleep(5)
+
+        for playlist in self.playlists:
+            playlist.update()