fix: repair cross-package bugs so all tests pass and typecheck is clean

[stooit]

Summary

Fixes all failing tests and eliminates all type errors across the monorepo (packages/ui, packages/utils, apps/web). Final state: bun test → 13 pass / 0 fail, npx tsc --noEmit → 0 errors.

Bugs fixed

1. Renamed hook / stale import (apps/web/src/lib/api.ts) — the hook in packages/utils was renamed to useDebounce, but the app still imported the old name. Updated the consumer to import the real exported name so both the runtime import and the type check resolve.
2. Date formatting locale (packages/utils/src/format/date.ts) — formatDate was zero-padding the day (01/03/2024). Now formats 1 Mar 2024 as day/month/year with an unpadded day, matching the test's /^1/ expectation.
3. Missing accessibility attribute (packages/ui/.../Button.tsx) — icon-only buttons did not expose an accessible name. aria-label is now forwarded to the underlying <button>.
4. Stale closure sort bug (packages/ui/.../DataTable.tsx) — replaced the state expression that read a stale sortDir with a functional updater, so a second click correctly toggles to descending.

Supporting changes (not source bugs, but required to run/verify)

• bunfig.toml — wired up the already-installed @happy-dom/global-registrator preload so the UI tests have a DOM (previously failing with document is not defined). No new dependency.
• tsconfig.json + new bun.d.ts — added a triple-slash reference to the already-installed bun-types so bun:test resolves in test files, clearing the 4 TS2307 errors. Used a reference file rather than compilerOptions.types to preserve automatic @types/react discovery. No test files modified, no new dependency.

Constraints honoured

• No test files modified.
• No new dependencies added (both happy-dom and bun-types were already in node_modules).
• Only the changes required to make tests pass and typecheck clean.

Reviewer notes / assumptions

• The DataTable "stale closure" test passes with or without the functional-updater change (each click is a discrete committed render). The functional updater is kept as the correct idiom and guards against future batching regressions, but it was not strictly required by the current test.
• formatDate uses en-GB to get unpadded-day day/month/year output. An en-AU + formatToParts alternative was considered; either is defensible.
• The icon-only Button falls back to a generic accessible name when no aria-label is provided (to satisfy the "still renders" test); a stricter type-level requirement would need a test edit, which is out of scope here.