fix: repair 4 cross-package bugs and resolve type errors

[stooit]

Summary

Fixes all failing tests and type errors in the monorepo. bun run test → 13 pass / 0 fail; bunx tsc --noEmit → 0 errors (also verified green under TZ=America/New_York). No test files modified, no dependencies added.

Bugs fixed

• apps/web/src/lib/api.ts — renamed hook. The hook in packages/utils was renamed to useDebounce (correctly exported), but api.ts still imported the old useSearchDebounce/useThrottle names. Now imports useDebounce and re-exports it as useSearchDebounce (the name api.test.ts asserts). Verified useThrottle had no other consumers.
• packages/ui/.../Button.tsx — accessibility (WCAG 4.1.2). Icon-only buttons now always expose an accessible name via aria-label. Explicit label used as-is; otherwise falls back to plain-string children, else a neutral "Button" label (deliberately not purpose-specific, to avoid mislabelling e.g. a delete button). Dev-only warning fires at most once per distinct label.
• packages/ui/.../DataTable.tsx — sort toggle. Uses a functional setSortDir updater so ascending→descending toggling is correct across re-renders.
• packages/utils/.../date.ts — en-AU formatting. formatDate now renders day-first with no leading zero on the day (1/03/2024, not 01/03/2024) via formatToParts, and pins timeZone: "Australia/Sydney" for deterministic output regardless of host TZ.

Supporting change

• tsconfig.json — added "types": ["bun-types"] (already a devDependency) so bun:test resolves, and added apps/*/test/**/* to include so the web app's tests are type-checked. Eliminated the pre-existing Cannot find module 'bun:test' errors without editing any test file or adding a dependency.

Assumptions

• The bun:test type errors were pre-existing config gaps; resolving them via tsconfig (not test-file edits) was treated as in-scope for "eliminate all type errors".
• aria-label remains optional; discriminated-union enforcement would require changing a test's deliberately-unlabelled case, so it was left out of scope.

Verification

• bun run test → 13 pass / 0 fail
• bunx tsc --noEmit → exit 0
• Re-ran tests under TZ=America/New_York → still green
• Reviewed by the review subagent; the flagged blocker (misleading fallback label) was addressed.