Initial commit: Conflict Checker

Cross-discipline design-contradiction checker for construction drawing
sets. Standalone tool broken out from Iron_Bid; a pipeline stage may
later fold back into Iron_Bid.

Pipeline: PDF->images -> per-sheet assertion extraction -> deterministic
clustering by location -> per-cluster reasoning -> report.
Includes CLI (cli/run_check.py) and web UI (backend/main.py).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/.llm_cache/47572e3fe895bf8fa6c5bffc2bf0c784c08672a1b6d8f7ba849012e960821c1a.json

@@ -0,0 +1 @@
+{"conflicts": [{"conflict_id": "A1101_Building_C_Label_Missing", "category": "tag_or_reference_inconsistency", "severity": "medium", "confidence": "high", "location": "Site Plan, Area of Work", "disciplines": ["Architectural"], "sheets": ["A11.01"]}]}