feat(pptx): implement comprehensive PPTX parser with advanced extraction capabilities

- Introduced a complete solution for parsing PPTX files, extracting text, shapes, images, slides, and metadata.
- Enhanced text extraction with formatting preservation and shape analysis.
- Added support for image extraction with optional OCR processing.
- Implemented slide-to-image conversion and comprehensive metadata extraction.
- Improved file validation and error handling for robust parsing.

Author: maxpill