fix(harness-opencode): disable questions in headless sessions (#19801)

## Background

OpenCode exposes a native `question` tool for interactive clarification.
The OpenCode harness bridge is headless and cannot answer that tool, but
its server configuration currently leaves the tool enabled. If a model
calls it, AI SDK reports an unavailable tool while OpenCode waits
indefinitely for a reply.

## Changes

- deny OpenCode's interactive `question` permission in harness-managed
sessions
- add a regression test for the server configuration
- add a patch changeset

## Testing

- `pnpm turbo build --filter=@ai-sdk/harness-opencode...`
- `pnpm test` in `packages/harness-opencode` (75 tests)
- `pnpm check`
- `pnpm type-check:full`

Fixes #19800

---------

Co-authored-by: Felix Arntz <flixos90@gmail.com>