feat(issue-filing): harden final report proofs for handoff and mutations (#191)

Add assess_issue_filing_final_report and supporting checks for Controller
Handoff (issue_filing role), exact issue number/title, full 40-char SHAs,
per-mutation capability proof, single-mutation scope statements, and
duplicate-search summaries. Workflow skill documents the issue-filing
handoff fields.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

skills/llm-project-workflow/SKILL.md

@@ -462,6 +462,12 @@ Role-specific fields (append to the compact block):
 - review/merge tasks: `Selected PR:`, `Reviewer eligibility:`,
   `Pinned reviewed head:`, `Review decision:`, `Merge result:`,
   `Linked issue status:`, `Cleanup status:`
+- issue-filing tasks (#191): `Issue created or updated:`, `Related issues:`;
+  body must cite exact issue number/title, duplicate-search summary (issues
+  searched, closest matches, why update rejected / new issue justified), full
+  40-char SHAs when citing commits, exact mutation capability per change, and
+  `Only mutation(s):` when a single mutation was performed
+  (`review_proofs.assess_issue_filing_final_report`).
 - author tasks: `Selected issue:`, `Claim/comment status:`,
   `PR number opened:`, `No review/merge:` (explicit confirmation)
 - continuation tasks (#188): `Continuation mode:`, `Existing PR:`,