feat: implement annotation rendering functions for text highlighting and layout creation

feat: add parser utilities for cleaning Markdown and encoding PDFs to base64

refactor: streamline chunk creation by removing total_chunks parameter and updating chunk handling

refactor: simplify context enrichment by removing window context and integrating text splitter. Window context already in text_spliter's chunk_overlap parameter.

Initial commit: add project structure, core functionality, and dependencies for climate misinformation detection tool