feat(F-098): completed feature

work/artifacts/F-098/security.json

@@ -0,0 +1,13 @@
+{
+  "feature_id": "F-098",
+  "agent": "security",
+  "verdict": "APPROVED",
+  "summary": "The fallback writes NULL only for the incompatible backoffice identity and does not expose or alter API-key response behavior.",
+  "evidence": [
+    "The existing FK remains enforced",
+    "Valid identity_users audit IDs remain preserved",
+    "Backoffice settings saves do not bypass authentication",
+    "AI API key continues to be omitted from settings responses"
+  ],
+  "timestamp": "2026-08-20T20:38:40Z"
+}