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/7a1bb8d5dac63be4823ebddb85e6aebc6164a547b3169d6e48725d9944f8912b.json

@@ -0,0 +1 @@
+{"conflicts": [{"conflict_id": "A23.01_conflict_01", "category": "note_or_spec_contradiction", "severity": "low", "confidence": "high", "location": "General Notes and Finish Legend", "disciplines": ["Architectural"], "sheets": ["A23.01"]}]}