Support Edu Plus and Edu Pro account plans (#39316)

## What changed

- Recognize `edu_plus` and `edu_pro` as distinct education workspace plans across authentication, backend rate-limit mapping, and app-server account schemas.
- Include both plans in cloud configuration eligibility and use the education usage-limit behavior.
- Display the plans as `Edu Plus` and `Edu Pro` in the TUI status view.

## Testing

- Cover parsing, workspace classification, account and rate-limit responses, cloud configuration eligibility, usage-limit messages, and TUI display names for the new variants.

GitOrigin-RevId: bf8add780ae03a3c6d10c4f4afa0da262c37928e

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -14729,6 +14729,8 @@
           "enterprise_cbp_usage_based",
           "enterprise",
           "edu",
+          "edu_plus",
+          "edu_pro",
           "unknown"
         ],
         "type": "string"