fix: resolve cross-package test failures and type errors

[stooit]

Summary

Fixes all failing tests and type errors across the monorepo. bun run test → 13 pass / 0 fail; bunx tsc --noEmit → clean. No test files modified; no dependencies added.

Root causes & fixes

• apps/web/src/lib/api.ts — the hook was renamed in packages/utils (useThrottle → useDebounce), but the consumer still imported the old name. Updated the import to the current useDebounce export.
• packages/ui/.../Button/Button.tsx — icon-only buttons lacked an accessible name. Added the aria-label required for WCAG 4.1.2.
• packages/ui/.../DataTable/DataTable.tsx — fixed a stale-closure bug surfaced by the controlled re-render test.
• packages/utils/src/format/date.ts — date formatting produced US month-first / 2-digit-year output. Now uses en-AU via Intl.DateTimeFormat.formatToParts to emit day-first 1/03/2024 (unpadded day, zero-padded month, 4-digit year). en-AU ICU widens a numeric day to 2-digit when paired with a 2-digit month, so formatToParts keeps the day unpadded as the test requires.
• tsconfig.json — added bun-types to the types array (Bun globals; does not loosen strictness).

Verification

• bun run test: 13 passing across 5 files
• bunx tsc --noEmit: exit 0

Notes / assumptions

• The useThrottle→useDebounce rename in packages/utils was treated as intentional; the stale consumer was reconciled rather than reverting the rename.