feat(F-098): completed feature

work/artifacts/F-098/implementer.md

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+# F-098 — Implementer evidence
+
+## Root cause
+
+`store_settings.updated_by` references `identity_users(id)`, while admin authentication returns IDs from `backoffice_users`. Saving settings therefore raised a PostgreSQL foreign-key error and surfaced as HTTP 500.
+
+## Fix
+
+`settings.routes.ts` now checks whether the authenticated ID exists in `identity_users`; it writes the audit ID only when valid, otherwise writes `NULL`, preserving the FK and allowing backoffice settings saves.
+
+## Smoke test
+
+- Authenticated `PATCH /api/admin/settings` with AI provider, base URL, model, and prompts: HTTP 200.
+- Response includes saved AI configuration fields without exposing API key.
+- Test rows removed after the smoke test.
+- Services restarted successfully on ports 3000/3003/3004/3005.