fix: repair cross-package bugs and test config in monorepo

[stooit]

Summary

Fixes all failing tests and type errors across the bun-workspaces monorepo. bun test is now 13 pass / 0 fail and npx tsc --noEmit exits 0. Changes are minimal and targeted; no test files were modified and no dependencies were added.

Bugs fixed

• apps/web/src/lib/api.ts — imported a renamed hook under its old name. useThrottle → useDebounce (only useDebounce is exported from @e2e/utils). (fixes TS2305)
• packages/ui/.../Button/Button.tsx — icon-only button had no accessible name. Forwards aria-label to the <button>, satisfying getByRole('button', { name: ... }). (WCAG 4.1.2 Name, Role, Value)
• packages/ui/.../DataTable/DataTable.tsx — stale-closure bug: handleSort read sortDir from the captured closure, so re-clicking a column toggled against a stale value. Switched to the functional updater setSortDir(prev => ...).
• packages/utils/src/format/date.ts — explicit numeric field options forced M/D/Y ordering regardless of locale. Switched to { dateStyle: 'short' } so en-AU correctly produces day-first ordering.

Test/build config (config-only, no test files touched)

• bunfig.toml (root) — added preload = ["./packages/ui/test/setup.ts"] so the happy-dom GlobalRegistrator registers DOM globals when bun test runs from the repo root. Fixes ReferenceError: document is not defined.
• tsconfig.json — added "types": ["bun-types"] so bun:test imports resolve under tsc. (fixes TS2307)

Verification

• bun test → 13 pass, 0 fail
• npx tsc --noEmit → exit 0
• Independent review pass confirmed each change is a genuine fix (not a test-silencing hack) with no unintended behavioural changes.

Assumptions

• The intended hook name is useDebounce (the only export from @e2e/utils); the old useThrottle import was the bug.
• dateStyle: 'short' is the intended formatting approach for en-AU day-first output.