Show the planning check's state in the review view #198

Follow-up from #164 (PR #193).

Problem

PR #193 adds a planning check (PlanningCheck in runner/planning.ts). When the check fails, or has not finished yet, codeboost refuses each planning request with a 409 whose message starts "Planning is unavailable:" and names the reason. That is the only place the state shows.

The review view shows nothing about it when it loads. A person learns planning is off only after clicking Suggest edits or Draft. #164's acceptance asks for "a clear 'planning unavailable' state", and this half of it was left out of #193, because web/server.ts and web/public/* belonged to other work at the time.

Proposal

• Expose the check's state in the review payload: one of passed, running, failed (with the reason) or no vendor chosen. The state comes from PlanningCheck through productionPlanning.
• In the Plans screen:
  • While the check runs or has failed, show the state beside the planning controls, with the reason when it failed.
  • Disable Suggest edits and Draft until the check passes.

Also in scope (accepted limits recorded in #193, all needing web/server.ts)

• When a later startup step fails, startServer does not close planning. The check keeps running for any caller other than the CLI.
• A check deferred out of the Store transaction can start during shutdown. PlanningCheck cannot see the server's stopping flag.
• A Store read error during the check's wait is recorded as a refusal under the action ID, and is replayed on a resend.

Acceptance

• A review loaded while the check is running, has failed, or has no vendor chosen shows that state without a click.
• The planning buttons are disabled until the check passes.
• Browser tests for passed, running and failed states.