Improve hook selector readability with responsive option preview

[sonhyrd]

Summary

• add a selected-option preview pane to HookSelectorComponent so long choices are readable before selection
• keep the option list compact/single-line while rendering wrapped preview content
• use responsive layout: split list/preview on wide terminals, stacked layout on narrow terminals
• keep existing selector behavior (up/down, enter, left/right, cancel, timeout) intact

Verification

• bun test packages/coding-agent/test/hook-selector-overflow.test.ts
• bun test packages/coding-agent/test/tools/ask.test.ts