[Spec] ChatGPT Coding Setup 向导：定稿 A 与真实工具验收

[NOirBRight]

Decision and scope

Implement ADR-0019 and the user-finalized single-step A design as the production ChatGPT Coding Setup page. Build on the daily-browser account connection in #592 / PR #593. This issue covers the wizard; it does not close #567's real-client matrix or #592's pending real daily-browser acceptance.

Acceptance

• Five-step flow: daily-browser ChatGPT account → Tunnel and ordinary API key with Tunnels Read + Use → save immediately and instruct manual component restart with separate status recheck → authorize Codex Native2 Tunnel connector → harmless real tool request/result roundtrip.
• One current action, completed-step summaries, clear blocked reasons; resume from saved configuration and fresh checks. Legacy browser-only installation remains unfinished coding setup with credentials retained.
• No first-run text/full selector. No text-only, doctor-status-only, or simulated success; only a real tool roundtrip marks coding setup complete.
• Production page follows finalized A visual reference, including narrow layout and keyboard focus. No prototype switcher, scenario lab, dummy credentials, or mock actions.
• Preserve settings security, browser-session isolation, secret redaction, and existing Provider Connection ownership. Saving never restarts or waits for restart.
• Focused HTTP/UI tests plus strict local verification selected by docs/agents/verification-policy.md; review exact PR candidate.

Task graph

• UI and configuration flow: see child ticket created for this spec.
• Real tool probe and completion evidence: see child ticket created for this spec.
• Integration and acceptance: see child ticket created for this spec, blocked on both implementation tickets.

No release or installation is part of this issue.