fix(YouTube): bare except, browser leak, unbounded recursion, and other bugs

[tatenda-source]

• Bare except: in upload_video() catches KeyboardInterrupt/SystemExit and swallows errors
• Browser only closed on success path, leaked on exception
• generate_script(), generate_metadata(), generate_prompts() retry via unbounded recursion
• n_prompts = len(script) / 3 produces float used in prompt string
• ZeroDivisionError in combine() when no images generated
• IndexError on videos[0] when video list empty
• video_path not validated before upload
• generate_video() does not check return values of pipeline steps