fix: repair 5 failing tests across ui, utils, and web packages

[stooit]

Summary

Repairs all failing tests in the monorepo. Baseline was 8 pass / 5 fail (via bun run test) plus type errors; now 13 pass / 0 fail and npx tsc --noEmit is clean (exit 0). No test files modified, no dependencies added.

Bugs fixed

• Renamed hook (packages/utils → apps/web). A debounce hook was renamed upstream but apps/web/src/lib/api.ts still imported the old name. @e2e/utils now exports useSearchDebounce (alias of useDebounce, same identity) and the consumer import is reconciled. (fixes api.test.ts)
• Missing accessibility attribute (packages/ui Button). aria-label was destructured but never applied to the <button> element. It's now forwarded, with a fallback accessible name for icon-only buttons (WCAG 2.2 SC 4.1.2). Uses React.Children.toArray + type guard so element children are never stringified. (fixes 2 Button.test.tsx cases)
• Wrong date format (packages/utils). formatDate returned 01/03/2024 (leading-zero day). en-AU forces a 2-digit day regardless of day: "numeric" under this ICU build; switched to en-GB, which shares AU day/month/year ordering and / separator but honours un-padded day → 1/03/2024. The 15/06/2024 case is unaffected. (fixes date.test.ts)
• Stale-closure bug (packages/ui DataTable). Sort direction was read from a captured variable. Sort key + direction collapsed into a single useState object updated by one pure functional updater — StrictMode-safe, no stale read. (keeps the "sorts descending on second click" test green)
• Typecheck (tsconfig.json). Registered the already-installed bun-types with the compiler, clearing 4 pre-existing Cannot find module 'bun:test' errors.

Verification

• bun run test -> 13 pass / 0 fail
• npx tsc --noEmit -> exit 0
• Independent review: no blockers, all fixes confirmed to address root causes (ICU day-padding and StrictMode purity claims empirically falsification-tested).

Assumptions & notes

• Ran tests via bun run test (the npm script), which preloads the happy-dom setup. Plain bun test reports false document is not defined errors because the preload isn't applied.
• Scope kept to what the tests require. Reviewer flagged non-blocking follow-ups outside this scope: type-level enforcement of aria-label on icon-only buttons, formatDate/formatDateTime locale consistency, and keeping the "search" alias in the consumer rather than the shared package.