fix(validator): align final-report validator with canonical schema (Closes #698)

Fixes the final-report validator defects from Issue #698 (original lead
plus the independent reproduction recorded during the PR #703 formal
review, comment 11246):

- Legacy fields: the review/merger required-field tables no longer demand
  'Pinned reviewed head', 'Scratch worktree used', 'Worktree path',
  'Worktree dirty', 'Mutations', 'Next', 'Issue/PR', 'Branch/SHA', or
  'Files changed' — names the canonical review-merge-final-report schema
  forbids or replaces. The canonical names ('Reviewed head SHA', 'Review
  worktree path/dirty', 'Safe next action', mutation categories) are
  required instead, with backward-compatible aliases where the schema
  permits them.
- Structured proof: workflow-load helper results are recognized in
  colon, key=value, and JSON renderings; validation pass proof is
  accepted anywhere in the Validation field value (for example
  'focused 50 passed; full 2665 passed').
- Mutation inference: review mutations are inferred only from
  authoritative evidence (performed=true and not gated); read-only
  diagnostics and pre-API rejections no longer count as mutations.
- Lease release vs cleanup: canonical reviewer lease release (release
  tool call or terminal phase=released marker) is lease lifecycle, not
  post-merge cleanup, and no longer triggers the branch/worktree cleanup
  checklist; genuine delete/remove claims still require full proof.
- Blocked reports: a legitimately blocked run that states an explicit
  'Reviewed/Candidate head SHA: none' with no verdict, merge, or started
  validation owes no head proofs; approval-time and merge-time live-head
  proofs are demanded only once the corresponding phase begins, and a
  report that states no head at all still fails closed.
- action_log robustness: malformed (non-dict) entries and non-list logs
  are reported as clear sanitized findings (position and type only, no
  content echo) instead of crashing with AttributeError; a defective
  validator rule now fails closed with a sanitized block finding rather
  than raising a secondary exception.

27 new regression tests, including canonical fixtures modeled on the
PR #703 formal-review handoff and the blocked preflight report from the
prior #698 reproductions. Two legacy-field test fixtures updated to the
canonical schema. Full suite: 2663 passed, 6 skipped, 161 subtests.

Co-Authored-By: Claude Fable 5 <[email protected]>

post_merge_cleanup_proof.py

@@ -86,6 +86,22 @@ _WRONG_BRANCH_RE = re.compile(
     r"deleted branch (?:does not match|!=|differs from) (?:merged )?pr head",
     re.IGNORECASE,
 )
+# #698: canonical reviewer lease lifecycle operations are NOT post-merge
+# cleanup. Releasing a reviewer PR lease (or posting its terminal
+# phase=released marker) happens after every review — merged or not — and
+# must never trigger the post-merge branch/worktree cleanup checklist.
+_LEASE_LIFECYCLE_RE = re.compile(
+    r"(?:gitea_release_reviewer_pr_lease|gitea_abandon_workflow_lease|"
+    r"release[d]? (?:the )?(?:reviewer|workflow) (?:pr )?lease|"
+    r"reviewer (?:pr )?lease release[d]?|"
+    r"lease (?:marker|comment).{0,40}phase\s*[:=]\s*released|"
+    r"phase\s*[:=]\s*released)",
+    re.IGNORECASE,
+)
+_CLEANUP_MUTATIONS_VALUE_RE = re.compile(
+    r"cleanup mutations\s*:\s*([^\n]+)",
+    re.IGNORECASE,
+)
 
 
 def _claims_remote_delete(text: str) -> bool:
@@ -204,16 +220,19 @@ def assess_post_merge_cleanup_proof(
             for field in _worktree_cleanup_fields_present(text)
         )
 
-    if (remote_delete or worktree_remove) and not (remote_delete or worktree_remove):
-        pass
-
     if not remote_delete and not worktree_remove:
-        cleanup_mutations = re.search(
-            r"cleanup mutations\s*:\s*(?!none\b)\S",
-            text,
-            re.IGNORECASE,
+        value_match = _CLEANUP_MUTATIONS_VALUE_RE.search(text)
+        value = (value_match.group(1).strip() if value_match else "")
+        value_lower = value.lower()
+        substantive = bool(value) and value_lower not in {
+            "none", "n/a", "not applicable",
+        }
+        # #698: reviewer lease release / terminal lease markers are lease
+        # lifecycle, not post-merge cleanup — no checklist owed.
+        lease_lifecycle_only = substantive and bool(
+            _LEASE_LIFECYCLE_RE.search(value)
         )
-        if cleanup_mutations:
+        if substantive and not lease_lifecycle_only:
             reasons.append(
                 "cleanup mutations reported without post-merge cleanup proof checklist"
             )