docs: update PRD with actual implementation progress
- Updated progress table: Phase 3 is 95% complete, Phase 4 is 60% complete
- Marked all prompt_calls.py files as complete (saas, clover, bcbs_promise)
- Marked tin_npi_funcs.py, hybrid_smart_chunking_funcs.py, postprocessing_funcs.py, crosswalk_utils.py, dynamic_funcs.py as complete
- Noted 2 remaining universal_json_load calls in code_funcs.py (lines 498, 856)
- Documented aarete_derived.py dual-format support (intentional backward compatibility)
- Added comprehensive implementation status summary section
- Updated Phase 3 and Phase 4 checklists with actual completion status
- Added statistics: 26 files modified, ~350 lines net reduction, 20+ commits
ppanchigar
9e3fe81fe5