fix(tui): keep permission prompt buttons visible for long commands

[KDB-Wind]

Issue for this PR

Closes #40793

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

The TUI permission prompt rendered command text as a plain <text> node with no wrapping and no height limit. A long shell command pushed the Allow/Reject buttons off-screen, so the request could not be answered. The desktop app has the same bug (#40968).

All text-based permission bodies (bash, task, webfetch, websearch, read, glob, grep, list) now render in a bounded scrollbox with wrapMode="word". The buttons stay visible; long content scrolls instead of overflowing.

How did you verify your code works?

• Added packages/tui/test/cli/tui/permission-prompt.test.tsx. It mounts PermissionPrompt, injects a permission request via message.part.updated, and checks that:
  • a 2000+ char command keeps all three buttons visible and its tail outside the viewport
  • a command with a single unbroken 2000+ char token does the same
  • a long read path keeps the buttons visible
  • a short command renders fully
• The long-command test fails with the old plain <text> rendering and passes with the fix (verified both ways).
• bun run typecheck in packages/tui: clean.
• Full packages/tui suite: 196 pass. One pre-existing Windows-only failure in runtime.test.tsx, unrelated.

Screenshots / recordings

Rendered with the TUI renderer test harness (15-row terminal, long heredoc commit command).

Before (dev): command text is clipped with no scrollbar, the tail is unreachable.

┃
┃  △ Permission required
┃    # Shell command
┃
┃  $ git commit -m "$(cat <<'EOF'
┃  fix: long description line fix: long description line fix: long description line fix: long
┃  description line fix: long description line fix: long description line fix: long description
┃  line fix: long description line fix: long description line fix: long description line fix:
┃  long description line fix: long description line fix: long description line fix: long
┃  description line fix: long description line fix: long description line fix: long description
┃  line fix: long description line fix: long description line fix: long description line fix:
┃
┃
┃   Allow once   Allow always   Reject                 ctrl+f fullscreen  ⇆ select  enter confirm
┃

After (this PR): the body is a bounded scroll area with a scrollbar; the full command is reachable and the buttons stay visible.

┃
┃  △ Permission required
┃    # Shell command
┃
┃  $ git commit -m "$(cat <<'EOF'                                                               █
┃  fix: long description line fix: long description line fix: long description line fix: long   █
┃  description line fix: long description line fix: long description line fix: long description █
┃  line fix: long description line fix: long description line fix: long description line fix:   ▀
┃  long description line fix: long description line fix: long description line fix: long
┃  description line fix: long description line fix: long description line fix: long description
┃  line fix: long description line fix: long description line fix: long description line fix:
┃
┃
┃   Allow once   Allow always   Reject                 ctrl+f fullscreen  ⇆ select  enter confirm
┃

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

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