fix(select): wrap arrow-key navigation at list boundaries

[ywenhao]

Motivation

The task selector opened by vp run / vpr stops at the first and last entries. Users switching from nr expect Up on the first task to select the last, and Down on the last task to select the first. This also makes tasks near the end of a long list quicker to reach.

Refs voidzero-dev/vite-plus#2638. The implementation belongs to the shared vt_select component in this repository.

Changes

• Wrap State::move_up and State::move_down over the current selectable items and keep the selected row visible.
• Preserve no-op behavior for empty results and single-item lists. Group headings remain non-selectable, and wrapping is limited to the current filtered results.
• Add regression coverage for both boundaries, viewport scrolling, filtered results, grouped tasks, empty results, and a single result.

Vite+ will need to consume an updated Vite Task revision after this is merged. This does not change the separate top-level command picker opened by bare vp.