- New ServiceType.CODEX with CodexCredential (access_token + refresh_token + expiresAt)
- CodexRepository: query chatgpt.com/backend-api/wham/usage, auto refresh token 60min before expiry
- Import full auth.json in settings, supports automatic OAuth token refresh
- ChatGPT favicon SVG icon (ic_codex_logo.xml)
- Dashboard card shows 5h/Weekly usage windows with reset times
- Update AGENTS.md and README.md with Codex service info
