feat: add create-issue final-report verifier (#337)

Extend review_proofs with assess_create_issue_final_report to enforce
workflow-source proof, create-issue handoff schema fields, and rejection
of work-issue/review-merge cross-mode handoff fields.

Closes #337

tests/test_llm_workflow_split.py

@@ -97,4 +97,10 @@ def test_merge_pr_template_references_workflow():
 
 def test_start_issue_template_references_work_issue_workflow():
     text = (SKILL_DIR / "templates" / "start-issue.md").read_text(encoding="utf-8")
-    assert "workflows/work-issue.md" in text
+    assert "workflows/work-issue.md" in text
+
+
+def test_create_issue_final_report_verifier_exported():
+    from review_proofs import assess_create_issue_final_report
+
+    assert callable(assess_create_issue_final_report)