feat(provider-codex): support MCP elicitation requests (fixes Computer Use perms, etc)

[smsunarto]

Human comments

What was wrong

BB did not handle Codex's mcpServer/elicitation/request, so app-access requests were silently declined and other MCP elicitations could not collect answers.

What changed

• Computer Use: native app icons, session/persistent approval, and Decline. High-risk warnings remain visible. Codex owns permission storage.
• Forms: typed text, numbers, booleans, and choices with defaults and validation. Unsupported schemas cannot be accepted.
• URLs: show the destination and open only on user action. Acceptance means the URL opened, not that sign-in completed.
• Shared BB styling: compact composer cards, visible actions, and a subtle scroll fade. CLI/SDK responses and the provider guide cover all request kinds.
• Contracts: experimental plugin-owned headings, SDK 0.4.48, and host daemon protocol 183.

How you verified

• Decoder regressions failed before the fix. Provider, contract, renderer, SDK, and guide tests/typechecks pass.
• Live BB: real Calculator request and decline, typed form submission, required-field errors, scrolling, and URL actions. Live grant persistence remains unverified.
• CI: 12 checks passed, 2 skipped.

Screenshots

Computer Use

Structured form

Validation

URL request

AGENT GENERATED