feat: require live PR head re-pin before conflict-fix classification (Closes #522)

Treat inventory mergeable/head as advisory. Add classification helper and
MCP tool so author sessions re-pin the live PR head before creating a
conflict-fix worktree, skip stale inventory false-negatives, and prove
classification in final reports.

review_proofs.py

@@ -5540,6 +5540,15 @@ def assess_already_landed_classification_report(report_text, **kwargs):
     return _assess(report_text, **kwargs)
 
 
+def assess_conflict_fix_classification_final_report(report_text, **kwargs):
+    """#522: require live PR head re-pin before conflict-fix classification."""
+    from conflict_fix_classification import (
+        assess_conflict_fix_classification_final_report as _assess,
+    )
+
+    return _assess(report_text, **kwargs)
+
+
 def assess_prior_blocker_skip_proof(report_text, **kwargs):
     """#318: require live blocker proof before skipping earlier open PRs."""
     from reviewer_blocker_skip import assess_prior_blocker_skip_proof as _assess