Constrain PickerMenu description width to the terminal's real width

[Ref34t]

Fixes #986.

(Reopened from #987, which was accidentally branched from wordpress-framework-support instead of main and dragged in unrelated files. This branch is based on current main and contains only the fix below.)

The bug

Multi-select options with a description wrapped that text in a Box fixed at width={56}, regardless of the actual terminal width. On a narrow terminal this let the row render wider than the physical screen. The terminal's own line-wrapping (which Ink doesn't control) then misaligned Ink's cursor bookkeeping for every row after it — producing the overlapping/corrupted text in #986: checkbox labels merging into their descriptions (No + Skip custom scouts... → NoSkip custom scouts...), the Confirm button overlapping the last option's wrapped tail, and — on a second checklist in the same run — fragments of multiple different tool names bleeding together (FrillrebaseghtVM reads like "Frill" + "Firebase" + something ending "...VM" overlapping).

How I found it

Reproduced headlessly with ink-testing-library, patching its Stdout prototype to drive real widths (100 → 40 columns) since the library hardcodes 100 columns with no override. The message text reflowed correctly at every width; the description did not — identical wrap points from 100 down to 40 columns, confirming the fixed width never adapted.

The fix

descriptionWidth() in PickerMenu.tsx reads the live terminal width via Ink's useStdout() and clamps to it — floor of 20 characters, cap of 56 (the original constant, kept as an upper bound on wide terminals), accounting for the outer margin, the per-column share when the grid has more than one column, and the description's own indent.

Verified the fix directly: re-ran the same headless harness after the change — longest rendered line now tracks the terminal width exactly (100 cols → 62, 60 cols → 60, 40 cols → 40), instead of staying near-constant regardless of width.

Also found while investigating

• The playground demo for PickerMenu (InputDemo.tsx) never exercises the description prop at all — the exact code path that broke had zero coverage in the one place built to catch this visually.
• ink-testing-library is a real devDependency but was unused anywhere in this repo before this fix. This is the first .tsx test file — vitest.config.ts was already configured for it (esbuild: { jsx: 'automatic' }), just never exercised.

Testing

• pnpm build — clean, including smoke + warlock security tests
• pnpm test — 1544/1544 passing against current main (1541 existing + 3 new)
• pnpm lint — 0 errors
• New test: src/ui/tui/primitives/__tests__/PickerMenu.test.tsx, using the same monkeypatch-the-Stdout-prototype technique used to find the bug, kept as a permanent regression test

Opened as a draft — background on how this surfaced (a real self-driving run against a Laravel/Vue app, not a wizard-workbench fixture) is in #986.

[Ref34t]

Closing this. On investigation the premise is wrong — see #986 (comment) for the detail.

Short version: Output clips every line to the terminal width (renderer.js builds the buffer at the root's computed width and slices with sliceAnsi), so an over-wide description Box can't cause the terminal-level wrap this patch assumed. The corruption also shows up on screens where the description Box never renders at all, and my terminal was ≥88 columns — where descriptionWidth() returns exactly 56, identical to the current hardcoded value. So this would have been a no-op for the reported bug.

The actual trigger looks to be resizing the terminal window mid-run: Ink's resized() only clears when width decreases.

Not reopening as a hardening change either — I'd rather not add a speculative patch to a component I no longer think is at fault. If narrow-terminal support for option descriptions is something you want, happy to raise it separately on its own merits.