fix: make codex queue storage pg authoritative

docs/reference/arch.md

@@ -26,6 +26,10 @@
       - Includes frontend gateway, task scheduler, project management, provider ingress, and other stateless modules
       - Instances can scale horizontally; failure recovery requires no state synchronization
       - Only the frontend gateway and provider ingress are public; core REST APIs and PostgreSQL remain on the Docker internal network
+    - Frontend Time Zone Policy
+      - All UniDesk frontend timestamps, dates, clocks, update times, heartbeat times, Trace times, Gantt axis labels, export date stamps, and `datetime-local` values must render as Beijing time.
+      - Beijing time means IANA timezone `Asia/Shanghai` / UTC+8, regardless of the browser timezone, host system timezone, container timezone, or server-side `project.timezone` value.
+      - Frontend code must use the shared formatter and input conversion helpers in `src/components/frontend/src/time.ts`; raw ISO/UTC timestamps may appear only inside explicitly opened raw JSON views.
     - PostgreSQL Database
       - Deployed as a Docker container with a 10 GB named volume
       - Stores all task metadata, node heartbeats, resource labels, and business state