Add Codex Auth support in account management so selected accounts can
complete a Codex-compatible OAuth login flow and export usable auth.json
files.
This commit includes:
- account-management UI entrypoints for Codex Auth login and auth.json download
- backend SSE routes for single-account and batch Codex Auth login execution
- persistence of freshly returned Codex-compatible tokens back into the account database
- Codex auth export support for direct auth.json download and batch zip packaging
- tests covering the Codex Auth login flow and export behavior
The OTP verification failure was caused by manually sending a second OTP after
password verification. The flow now reuses the existing proven login path:
login re-entry, password verification, automatic OTP reception, consent page
handling, workspace selection, and OAuth callback exchange.
Successful logins now also persist workspace_id together with the refreshed
Codex-compatible tokens, making later re-export of auth.json possible without
requiring the browser-downloaded file to still exist locally.
Change-Id: I59df518ef4dc05f8bc52c734dd1b738fcb0b7a4e
