fix: repair cross-package bugs so all tests and typecheck pass

[stooit]

Summary

Fixes all failing tests and eliminates all tsc --noEmit errors in the monorepo. Bugs spanned three packages. Only source code was changed — no test files modified, no dependencies added.

Result: 13 pass / 0 fail · npx tsc --noEmit clean (exit 0).

Fixes

• apps/web/src/lib/api.ts — stale import: useThrottle was renamed to useDebounce in packages/utils but the consumer still imported the old name (TS2305). Updated the import and the useSearchDebounce re-export to use useDebounce. Utils package left untouched as the source of truth.
• packages/ui/.../Button.tsx — aria-label was destructured but never applied to the <button>. Now passed through, giving icon-only buttons an accessible name (WCAG 4.1.2). A dev-only console.warn fires when an iconOnly button has no label (this is the expected warning visible in test output).
• packages/ui/.../DataTable.tsx — stale-closure sort bug caught by the controlled re-render test. Consolidated the two separate useStates (key + dir) into one atomic SortState<T> updated via the functional updater form, so direction toggles correctly across re-renders and stays StrictMode-safe.
• packages/utils/.../date.ts — formatDate zero-padded the day. Switched to Intl.DateTimeFormat.formatToParts to un-pad the day only, yielding day-first non-padded output (2024-03-01 → 1/03/2024) as the test expects.
• tsconfig.json — added "types": ["bun-types"] so bun:test resolves under tsc --noEmit (cleared 4 pre-existing TS2307 errors). bun-types was already a devDependency.

Assumptions

• The plain bun test invocation in the task lacks the DOM preload; the repo's own package.json test script uses --preload ./packages/ui/test/setup.ts, so verification was run with that (the document is not defined errors were a harness config artefact, not a source bug).
• formatDate's resulting D/MM/YYYY shape is what the tests assert, so it was preserved even though it's a hybrid of standard AU short-date conventions.

Reviewer notes (out of scope, not fixed)

Flagged during review but beyond what the tests require: sortable <th> headers are click-only (no keyboard handler — likely WCAG 2.1.1); the icon-only fallback label "Button" technically satisfies 4.1.2 but hides genuinely unlabelled controls from linters; the date formatter is now module-scoped (caches TZ at import). Left as-is to honour "fix only what the tests require."

Test plan

bun test packages/utils/test packages/ui/test apps/web/test --preload ./packages/ui/test/setup.ts
npx tsc --noEmit