fix: repair failing tests across ui/utils/web packages

[stooit]

Summary

Fixes all 9 failing tests and 5 type errors in the monorepo. Suite now reports 13 pass / 0 fail and tsc --noEmit is clean.

Root causes & fixes

• apps/web/src/lib/api.ts — imported a stale hook name useThrottle from @e2e/utils; the hook was renamed to useDebounce. Updated the import and re-export. (useSearchDebounce has no call sites, so no behavioural change.)
• packages/utils/src/format/date.ts — formatDate produced 01/03/2024 (zero-padded day) under en-AU; the test requires 1/03/2024. Switched to Intl.DateTimeFormat.formatToParts and stripped the day's leading zero. Month stays padded, year stays 4-digit; formatDateTime/formatAUD unaffected.
• packages/ui/src/components/Button/Button.tsx — icon-only buttons rendered with no accessible name (WCAG 2.2 SC 4.1.2). Now bind aria-label, falling back to string children, plus a dev-only console.warn when an icon-only button lacks a label.
• packages/ui/src/components/DataTable/DataTable.tsx — sort toggle changed to a functional setState update to harden against stale-closure/batched-update issues.

Test-config fixes (no source-behaviour impact)

• bunfig.toml — environment = "happy-dom" is not a recognised Bun [test] key and was silently inert; replaced with a preload registering the happy-dom setup so bun test provides a DOM standalone. This unblocked the document is not defined errors.
• tsconfig.json — added bun-types to compilerOptions.types to resolve the bun:test module (fixed 4x TS2307).

Constraints honoured

• No test files modified (verified via git diff --name-only).
• No new dependencies added — only pre-installed bun-types and @happy-dom/global-registrator used; package.json/lockfile untouched.

Verification

• bun test -> 13 pass / 0 fail
• tsc --noEmit -> exit 0, zero errors

Reviewer notes / assumptions

• The Button aria-label fallback to a generic label is required by Button.test.tsx (asserts the attribute is non-null even when no label is passed). A stricter approach would fail that test, so the dev console.warn surfaces the misuse instead.
• The DataTable "stale closure" fix is defensive — the original already passed under separate click events; the functional update is idiomatic hardening.
• Follow-ups out of scope for this test-fix pass: DataTable sortable headers are keyboard-inaccessible (WCAG 2.1.1 Level A); repo has no lockfile (bun-types: "latest" unpinned).