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]>

tests/test_review_proofs.py

@@ -957,17 +957,20 @@ class TestControllerHandoff(unittest.TestCase):
             if not line.startswith("- Workspace mutations:"))
         result = assess_controller_handoff(review_base, role="review")
         self.assertEqual(result["verdict"], "incomplete")
-        self.assertIn("Pinned reviewed head", result["missing_fields"])
-        self.assertIn("Worktree path", result["missing_fields"])
+        # #698: the canonical schema forbids the legacy fields, so the
+        # validator must demand the canonical names instead.
+        self.assertIn("Reviewed head SHA", result["missing_fields"])
+        self.assertIn("Review worktree path", result["missing_fields"])
         self.assertIn("Merge result", result["missing_fields"])
+        for legacy in ("Pinned reviewed head", "Scratch worktree used"):
+            self.assertNotIn(legacy, result["missing_fields"])
 
         complete = review_base + "\n" + "\n".join([
             "- Selected PR: #999",
             "- Reviewer eligibility: passed",
-            "- Pinned reviewed head: 0fdc8f582026b72a229d59a172c0a63ac4aaeaf9",
-            "- Worktree path: /repo/branches/review-pr-999",
-            "- Worktree dirty: no",
-            "- Scratch worktree used: yes (/repo/branches/review-pr-999)",
+            "- Reviewed head SHA: 0fdc8f582026b72a229d59a172c0a63ac4aaeaf9",
+            "- Review worktree path: /repo/branches/review-pr-999",
+            "- Review worktree dirty before validation: no",
             "- Unrelated local mutations: none",
             "- Review decision: approve",
             "- Merge result: merged",
@@ -1125,10 +1128,9 @@ class TestReviewHandoffPreciseMutationCategories(unittest.TestCase):
         "- Safety: no self-review; no self-merge; no secrets",
         "- Selected PR: #999",
         "- Reviewer eligibility: passed",
-        "- Pinned reviewed head: 0fdc8f582026b72a229d59a172c0a63ac4aaeaf9",
+        "- Reviewed head SHA: 0fdc8f582026b72a229d59a172c0a63ac4aaeaf9",
         "- Worktree path: /repo/branches/review-pr-999",
         "- Worktree dirty: no",
-        "- Scratch worktree used: yes (/repo/branches/review-pr-999)",
         "- Unrelated local mutations: none",
         "- Review decision: approve",
         "- Merge result: none",