fix: resolve 4 cross-package bugs causing test failures

[stooit]

Summary

Fixes all 9 failing tests across 5 test files in this multi-package TypeScript monorepo.

Changes

• apps/web/src/lib/api.ts — Fixed renamed hook import: useThrottle → useDebounce, re-exported as useSearchDebounce
• packages/ui/src/components/Button/Button.tsx — Pass through aria-label prop for icon-only button accessibility
• packages/ui/src/components/DataTable/DataTable.tsx — Use functional state update to fix stale closure bug in sort handler
• packages/utils/src/format/date.ts — Use d/MM/yyyy (non-padded day) format instead of dd/MM/yyyy
• bunfig.toml + packages/ui/bunfig.toml — Configure happy-dom preload for UI component tests

Verification

• bun test → 13 pass, 0 fail
• npx tsc --noEmit → only expected bun:test module resolution errors in test files (no source code type errors)

Assumptions

• The bun:test TypeScript module resolution errors are pre-existing and expected (requires @types/bun which is not in dependencies)
• happy-dom was already available in node_modules; used its GlobalRegistrator as a preload since bun 1.3.14 ignores [test] environment in bunfig.toml