Refactor: log task httpx exceptions as errors.

[arabcoders]

• Added explicit handling for httpx.HTTPError in the task handlers, returning user-friendly error messages when network-related errors occur.
• Improved error logging in the dispatch method to include both the message and error details from TaskFailure results.
• Clarified warning logs for unexpected handler results in the dispatcher.
• Refactored the task dispatcher method to track dispatched tasks and their results, updating success and failure statistics more accurately.
• Updated the FAQ.md to reflect the change from browser to generic in yt-dlp extractor usage instructions, ensuring consistency and clarity for users.