docs: add backlog item 999.1 — rewrite E2E tests for OIDC auth

.planning/ROADMAP.md

@@ -274,3 +274,13 @@ Plans:
 | 21. Item & Catalog Detail Pages | v2.0 | 1/1 | Complete    | 2026-04-06 |
 | 22. Add-from-Catalog & Thread Integration | v2.0 | 2/2 | Complete    | 2026-04-06 |
 | 23. Manual Entry Fallback | v2.0 | 1/1 | Complete    | 2026-04-06 |
+
+## Backlog
+
+### Phase 999.1: Rewrite E2E Tests for OIDC Auth (BACKLOG)
+**Goal**: E2E tests currently expect local username/password login but auth moved to external OIDC (Logto). Rewrite with mock OIDC provider or API-key-based auth bypass. Seed migration to Postgres is already done.
+**Requirements**: TBD
+**Plans**: TBD
+
+Plans:
+- [ ] TBD (promote with /gsd:review-backlog when ready)