Drop Docling, PyMuPDF-only: fast multi-page PDF extraction, RL handles refinement by SpandanM110

Fix Docker build: add system libs, PyMuPDF fallback for table extraction by SpandanM110

Add system libs for Docling PDF processing (libxcb, libGL, poppler) by SpandanM110

Switch to Docker SDK with FastAPI + mounted Gradio UI by SpandanM110

Initial submission: OCR Table RL Environment for OpenEnv RL Challenge by SpandanM110