fix: resolve failing tests and type errors across monorepo

[stooit]

Summary

• apps/web/src/lib/api.ts: update the stale useThrottle import to the renamed useDebounce export from @e2e/utils.
• packages/ui Button: apply aria-label to the <button>; icon-only buttons always get an accessible name (caller label → string child → generic "Button" fallback with a dev-only warning).
• packages/ui DataTable: fix a stale closure in sort toggling by using the functional setSortDir(prev => ...).
• packages/utils formatDate: keep en-AU day-first order but drop the leading zero on the day (1/03/2024).
• bunfig.toml: preload the existing happy-dom setup. Bun has no environment option, so running bun test directly failed with document is not defined.
• tsconfig.json: add types: ["bun-types"] (already installed) so bun:test resolves.

Verification

bun test passes 13/13 and tsc --noEmit reports no errors.

Assumptions / notes

• No test files were changed and no dependencies were added.
• One Button test requires a non-null aria-label even when the caller passes none, so the component falls back to the generic "Button". Screen-reader users get little from that name, so callers should pass a real label; the dev warning is there to prompt them.
• formatDate now gives 1/03/2024 (day unpadded, month padded). formatDateTime still gives 1/3/24 and was left as is because no failing test covers it.