/experimental ask-user should render Markdown tables correctly

### Describe the feature or problem you'd like to solve

When /experimental ask-user returns content that includes a Markdown table, the table does not render correctly in the terminal UI. This makes structured comparisons hard to read and reduces the usefulness of ask_user for workflows where the user needs to choose between options, review tradeoffs, or inspect tabular data.

### Proposed solution

Render GitHub-flavored Markdown tables correctly in /experimental ask-user, with proper column alignment, borders or spacing, and wrapping behavior that remains readable in narrower terminal widths.

### Example prompts or workflows

_No response_

### Additional context

Expected behavior: tables should be readable and preserve row/column structure inside the /experimental ask-user flow.

Actual behavior: table formatting breaks, so columns collapse or become visually misaligned.

Start by locating the /experimental ask-user terminal UI entry point and its Markdown rendering path. Reproduce the issue with a GitHub-flavored Markdown table at narrow and normal terminal widths, then verify that columns remain aligned and readable while preserving row and column structure.

Written by the indexing model from the issue text.