feat(review-workflow): raise A-bar with capability, sweep, live-state, and role-boundary proofs (#179)

Extends review_proofs.py with the four #179 proofs, the successor set to
the #173 checkout/inventory proofs:

- assess_capability_evidence: a capability claim (review_pr, merge_pr, ...)
  counts only with exact evidence citing gitea_resolve_task_capability
  output or equivalent runtime context; no claims at all fails closed.
- assess_sweep_evidence: secret/provenance sweeps must state the exact
  command/script/pattern/named method, the scope scanned, and a boolean
  result; vague summaries are downgraded and a missing sweep fails closed.
- assess_live_state_recheck: an explicit pre-mutation recheck must prove
  the PR is still open, the live head equals the pinned head (full
  40-hex), the base branch is unchanged, and blocking review state was
  checked and absent; not performing it fails closed.
- assess_role_boundary: a reviewer run using an author namespace (or vice
  versa) is clean only with an explicit justification; unreported
  namespace usage fails closed.

build_final_report now takes the four proofs as keyword arguments: any
missing or failed proof downgrades the grade, merge_allowed additionally
requires the proven live-state recheck, and a merge performed without it
is a blocked violation. Existing #173 semantics are unchanged otherwise;
gates only get stricter.

tests/test_review_proofs.py adds 29 tests covering the issue's harness
assertions: capability claims without evidence downgraded, vague sweeps
downgraded, missing/stale live-state recheck downgrades and blocks merge
(violation when a merge is claimed anyway), unjustified author-namespace
use downgraded, and the #173 positive baseline preserved.

SKILL.md sections F/G and the review-pr/merge-pr templates now require the
capability evidence, exact sweep, pre-verdict and pre-merge live-state
rechecks, and reviewer-namespace discipline.

Closes #179

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

skills/llm-project-workflow/templates/merge-pr.md

@@ -20,10 +20,21 @@ Steps:
    *If the current identity does not match the required role (or is the PR author), STOP. Relaunch/switch to the correct profile first.*
 2. Verify authenticated identity + active profile.
 3. Confirm PR #<pr>: author (not you), state open, mergeable, review approved. Check if PR body uses `Closes #N` or `Fixes #N`; if it uses `Implements #N` or `Refs #N`, manual closing will be needed in step 29.
-4. If any gate fails → STOP and report.
-4. Merge with explicit confirmation (e.g. confirmation="MERGE PR <pr>"),
-   optionally pinning the reviewed head SHA / changed-file set.
-5. Confirm remote master now contains the merge commit (or the expected changes if squash merged).
+4. Capability evidence (#179): cite the exact gitea_resolve_task_capability
+   output (or runtime context) proving merge_pr is allowed — a bare
+   "capability checks passed" claim is downgraded.
+5. Final live-state recheck (#179), immediately before the merge mutation —
+   re-read the live PR and prove:
+   - PR still open
+   - live head SHA still equals the pinned/reviewed head SHA
+   - base branch unchanged
+   - no undismissed REQUEST_CHANGES / blocking review state remains
+   If any recheck fails → STOP, re-pin, re-validate.
+6. If any gate fails → STOP and report.
+7. Merge with explicit confirmation (e.g. confirmation="MERGE PR <pr>"),
+   pinning the reviewed head SHA (expected_head_sha) and, where supported,
+   the changed-file set.
+8. Confirm remote master now contains the merge commit (or the expected changes if squash merged).
    *Note: Gitea PR "closed" state is NOT equivalent to "merged". Do not assume a closed PR succeeded without verifying the actual landed changes.*
 
 Then run the cleanup template (worktree-cleanup.md):