[test] Add unit tests for useListState in @termuijs/widgets

[pranvxag]

What problem does this solve?

packages/widgets/src/data/ListState.ts exports useListState — a state
hook that manages list selection, scroll offset, and disabled item
skipping. It has no test file despite containing non-trivial logic
around boundary clamping and disabled item navigation.

Proposed solution

Create packages/widgets/src/data/ListState.test.ts covering:

• useListState initializes with correct defaults
• setItems() updates items list
• setItems() clamps selectedIndex when new list is shorter
• selectNext() moves selection forward
• selectNext() skips disabled items
• selectNext() does not go past last item
• selectPrev() moves selection backward
• selectPrev() skips disabled items
• selectPrev() does not go below 0
• confirm() is callable without error (no-op placeholder)

Which package would this belong in?

@termuijs/widgets — packages/widgets/src/data/ListState.test.ts

GSSoC contributor?

• Yes. You contribute under GSSoC 2026 and want to work on this.
• No. You are filing a suggestion.

[github-actions]

✅ Auto-assigned to @pranvxag (issue opener).

Open your PR by 2026-06-29 (7 days). The bot frees this issue for another contributor after that date.

Reminders:

• ⭐ Star the repo first. The star-check job blocks your merge otherwise.
• PR title: type: short description
• Link this issue in your PR body: Closes #1749

Good luck. 🚀