feat: PDF preview, database integration, and improved error handling

refactor: remove obsolete OCR test file and enhance address extraction logic

Refactor: Replace Tesseract with DocTR and integrate LayoutLMv3-DocTR model

feat: Add .dockerignore, enhance UI to display receipt number and robustly handle bill-to, and update README with an additional dataset.

Updated Extraction Logic for more Robustness

feat: Add Phase 3 generalization scripts and clean up legacy files

Complete Version 0.5 with Streamlit UI and full pipeline