Feature/pine script v6 improvements

[zindankurt]

This pull request improves the Pine Script documentation PDF converter with Pine Script v6 compatibility, robust error handling, and a better PDF formatting. The original script had limitations that prevented reliable bulk downloads - it was also limit the pdf with narrow text structure - this improvement addresses these issues while maintaining backward compatibility.

Here is some key changes in detail:

• Updated URLs for current Pine Script v6 documentation and enhanced table of contents detection with fallback selectors.
• Replaced sys.exit() with graceful error handling so the script continues on individual failures instead of stopping entirely.
• Added progress tracking with success/failure counters and comprehensive error logging.
• Improved PDF quality by fixing relative image URLs to absolute URLs for proper image display.
• Added custom CSS for full-width content and sidebar removal.
• Changed to A3 page format with optimized margins and implemented temporary file processing with proper cleanup.
• Added automatic output directory creation and better progress feedback for improved reliability.