feat: add worktree cleanup audit integrity (Closes #404)

Reconcile before/after branches/ snapshots so preserved worktrees cannot
disappear without removal logs or explained state transitions.

- worktree_cleanup_audit.py: snapshot capture, disposition reconciliation
- gitea_capture_branches_worktree_snapshot, gitea_assess_worktree_cleanup_integrity
- Final-report rule author.worktree_cleanup_audit_proof
- worktree-cleanup.md bulk audit section
- tests/test_worktree_cleanup_audit.py (11 cases)

final_report_validator.py

@@ -568,6 +568,27 @@ def _rule_conflict_fix_push_proof(report_text: str) -> list[dict[str, str]]:
     )
 
 
+def _rule_worktree_cleanup_audit_proof(report_text: str) -> list[dict[str, str]]:
+    from worktree_cleanup_audit import assess_cleanup_audit_final_report
+
+    text = report_text or ""
+    if "cleanup audit" not in text.lower() and "reconciliation table" not in text.lower():
+        return []
+    result = assess_cleanup_audit_final_report(text)
+    if result.get("proven"):
+        return []
+    return _findings_from_reasons(
+        "author.worktree_cleanup_audit_proof",
+        result.get("reasons") or [],
+        field="Worktree cleanup audit",
+        severity="block",
+        safe_next_action=(
+            "include reconciliation table counts, disposition rows, and "
+            "final git worktree list proof"
+        ),
+    )
+
+
 def _rule_reviewer_validation_command(report_text: str) -> list[dict[str, str]]:
     text = report_text or ""
     if not _BARE_PYTEST_RE.search(text):
@@ -1130,6 +1151,7 @@ _RULES_BY_TASK: dict[str, list[Callable[..., list[dict[str, str]]]]] = {
         *_SHARED_ISSUE_LOCK_RULES,
         _rule_reviewer_vague_mutations_none,
         _rule_conflict_fix_push_proof,
+        _rule_worktree_cleanup_audit_proof,
     ],
     "issue_filing": [
         _rule_shared_controller_handoff,