fix: repair cross-package test failures and type errors

[stooit]

Summary

Fixes all failing tests and type errors in the monorepo. bun test is now 13/13 green and npx tsc --noEmit exits 0. No test files were modified and no dependencies were added.

Bugs spanned all three packages plus root tooling config; several were masked by a broken test DOM environment that had to be fixed first.

Changes

File	Fix
bunfig.toml	The [test] block used environment = "happy-dom", a Vitest/Jest key that Bun silently ignores — so @testing-library/react renders failed with document is not defined. Switched to preload = ["./packages/ui/test/setup.ts"], which registers the already-installed happy-dom global. This unblocked the Button + DataTable render tests.
tsconfig.json	Added "types": ["bun-types", "react"] so bun:test resolves under tsc (react re-added explicitly since specifying types disables automatic @types/* inclusion).
apps/web/src/lib/api.ts	The hook was renamed to useDebounce in packages/utils, but this file still imported the old useThrottle. Updated the import and the re-export, preserving the as useSearchDebounce alias the test consumes.
packages/utils/src/format/date.ts	formatDate zero-padded single-digit days (01/03/2024); the test expects a non-padded day-first format (1/03/2024). Adjusted the Intl.DateTimeFormat options accordingly. formatDateTime left untouched.
packages/ui/src/components/Button/Button.tsx	The destructured ariaLabel was never rendered, so icon-only buttons had no accessible name (WCAG 2.2 SC 4.1.2). Now renders aria-label for icon-only buttons (falling back to string children) with a dev-only console.warn when an icon-only button has no label. Visible-text buttons are unaffected.
packages/ui/src/components/DataTable/DataTable.tsx	Stale-closure bug: the sort-direction toggle read sortDir captured at handler-creation time, so a second click on the same column didn't flip to descending. Replaced with a functional setSortDir updater. Also removed the now-obsolete BUG: comments.

Verification

• bun test -> 13 pass / 0 fail (the icon-only aria-label line in output is an intentional console.warn from a passing WCAG test, not a failure)
• npx tsc --noEmit -> exit 0, no diagnostics

Assumptions

• DOM environment via preload was chosen because packages/ui/test/setup.ts and @happy-dom/global-registrator were already present — this honours the "no new dependencies" constraint.
• en-GB locale in formatDate produces the exact non-padded day-first string the test asserts.
• aria-label scoped to iconOnly so visible-text buttons keep their text as the accessible name.

Review

Reviewed by the review agent (independently re-ran the suite and tsc). One flagged item — stale BUG comments in DataTable.tsx — was fixed before commit.