feat(web): add question tool support to web UI

[R44VC0RP]

Summary

Adds support for the question tool in the web UI, fixing #7599.

Changes:

• Enable QuestionTool in web client (removed CLI-only restriction)
• Add question state management to global-sync context
• Create QuestionPrompt component with tabbed multi-question support
• Position question prompt above input in dock area (popunder style)
• Add question rendering to share/web view
• Wire up question respond/reject handlers in DataProvider

Status

WIP - Core functionality is working but design refinements are still in progress:

• [ ] Fine-tune spacing and visual polish
• [ ] Ensure seamless connection between question prompt and input box

Testing

1. Start dev servers:
   • API: cd packages/opencode && bun dev -- serve --port 5555
   • Vite: cd packages/app && bun dev
2. Open http://localhost:3000
3. Trigger a question tool (e.g., ask the AI to ask you questions)

Fixes #7599