fix: resolve failing tests and type errors across packages

[stooit]

Summary

• apps/web/src/lib/api.ts: import renamed useDebounce instead of removed useThrottle (keeps useSearchDebounce alias).
• packages/ui Button: apply aria-label for icon-only buttons (dev warning + "Button" fallback when missing, required by test).
• packages/ui DataTable: fix stale closure in handleSort via functional setSortDir.
• packages/utils formatDate: unpadded day, en-AU day-first ordering (1/03/2024).
• bunfig.toml: replace ignored vitest-style environment key with preload of existing happy-dom setup.
• tsconfig.json: add types: ["bun-types"] + DOM lib so bun:test resolves.

Verification

bun test → 13 pass / 0 fail; tsc --noEmit → exit 0. No test files modified, no deps added.

Assumptions / follow-ups

• Button test requires aria-label non-null even when none passed, so a generic fallback is used; consider making aria-label required for iconOnly.
• formatDateTime left unchanged (no test coverage).