fix(workflow): non-forgeable irrecoverable auth, merger consumer, exact-scope cleanup (#709)

Address formal review 434 REQUEST_CHANGES on PR #710:
- F1: replace caller operator_authorized with server-side HMAC auth artifacts
- F2: implement fail-closed merger consumption for prior-provenance only
- F3: enforce remote/org/repo/head on cross-profile load and clear

Co-Authored-By: Grok 4.5 (xAI) <[email protected]>

task_capability_map.py

@@ -127,15 +127,32 @@ TASK_CAPABILITY_MAP: dict[str, dict[str, str]] = {
         "permission": "gitea.pr.review",
         "role": "reviewer",
     },
-    # #709: truthful absence-of-proof recovery record (not applied cleanup).
+    # #709: truthful absence-of-proof recovery (server-side auth + record + consume).
+    # Dedicated mutation capability — gitea.read is insufficient (review 434 F1).
+    "issue_irrecoverable_provenance_authorization": {
+        "permission": "gitea.decision_lock.irrecoverable_recovery",
+        "role": "reconciler",
+    },
+    "gitea_issue_irrecoverable_provenance_authorization": {
+        "permission": "gitea.decision_lock.irrecoverable_recovery",
+        "role": "reconciler",
+    },
     "record_irrecoverable_decision_lock_provenance": {
-        "permission": "gitea.issue.comment",
+        "permission": "gitea.decision_lock.irrecoverable_recovery",
         "role": "reconciler",
     },
     "gitea_record_irrecoverable_decision_lock_provenance": {
-        "permission": "gitea.issue.comment",
+        "permission": "gitea.decision_lock.irrecoverable_recovery",
         "role": "reconciler",
     },
+    "consume_irrecoverable_decision_lock_provenance": {
+        "permission": "gitea.pr.merge",
+        "role": "merger",
+    },
+    "gitea_consume_irrecoverable_decision_lock_provenance": {
+        "permission": "gitea.pr.merge",
+        "role": "merger",
+    },
     "delete_branch": {
         "permission": "gitea.branch.delete",
         "role": "author",