fix: repair cross-package bugs failing tests and typecheck

[stooit]

Summary

Repairs four cross-package bugs so bun run test and tsc --noEmit are both green. No test files modified, no dependencies added.

Before: 8 pass / 5 fail, tsc --noEmit exits 2 (5 errors).
After: 13 pass / 0 fail, tsc --noEmit exits 0.

Fixes

1. apps/web/src/lib/api.ts — The utils hook was renamed useThrottle → useDebounce, but api.ts still imported and re-exported the old name. Updated the import and re-export to useDebounce, preserving the app-facing public name useSearchDebounce (a test asserts it is exported). Removed the now-false // BUG: comments. Fixes both api.test.ts failures and the TS2305 error.

2. packages/ui/src/components/Button/Button.tsx — Icon-only buttons emitted no accessible name (WCAG 2.2 SC 4.1.2). The aria-label prop is kept optional (a read-only test renders iconOnly with no label and expects the attribute present, so requiring it would break that test at type-check time). Added a runtime fallback accessible name plus a dev-only console.warn nudging callers toward a real label.

3. packages/utils/src/format/date.ts — formatDate zero-padded the day (01/03/2024); the test requires day-first without a leading zero. Replaced the Intl.DateTimeFormat body with a manual D/MM/YYYY build (1/03/2024, 15/06/2024), preserving the documented 4-digit-year contract. formatDateTime left untouched.

4. tsconfig.json — Added "types": ["bun-types"] so bun:test resolves in test files. Verified React/JSX type-checking is unchanged.

Assumptions / notes

• DataTable "stale closure" test was already passing — the described bug does not reproduce (handleSort recreated each render; the two clicks are separate React batches). No change made per "fix only what tests require".
• formatDate format choice: chose a manual build over dateStyle: "short" because the latter silently downgrades the year to 2 digits (24), regressing the documented DD/MM/YYYY contract.
• Button "Button" fallback label satisfies not.toBeNull() but is generic; the console.warn is the real enforcement pushing callers to supply a meaningful label.

Follow-ups (out of scope — would touch tests)

• formatDate vs formatDateTime disagree on month padding and year width (2024 vs 24); worth aligning.
• Both date helpers read local time, so UTC-stored timestamps can render the wrong day outside AU — pre-existing, not a regression.

Test plan

• bun run test → 13 pass, 0 fail
• ./node_modules/.bin/tsc --noEmit → exit 0, no errors
• Only the four intended files changed; no test files modified