fix(adr100): hash approval fingerprint for postgres

apps/api/src/services/adr100_remediation_service.py

@@ -11,6 +11,7 @@ T25: remediation queue items are now actionable without mutating incident state:
 from __future__ import annotations
 
 import asyncio
+import hashlib
 from datetime import datetime, timedelta, timezone
 from typing import Any, Literal, Protocol
 
@@ -770,7 +771,7 @@ def _approval_fingerprint(item: dict[str, Any]) -> str:
     playbook_id = str(item.get("playbook_id") or "")
     incident_id = str(item.get("incident_id") or "")
     basis = work_item_id or f"{incident_id}:{playbook_id}:{item.get('remediation_action') or ''}"
-    return f"adr100_playbook_authoring:{basis}"[:240]
+    return hashlib.sha256(f"adr100_playbook_authoring:{basis}".encode("utf-8")).hexdigest()
 
 
 def _approval_result_payload(