fix: repair failing tests and type errors across the monorepo

[stooit]

Summary

Fixes all failing tests and eliminates all type errors in the monorepo. bun test now reports 13 pass / 0 fail and tsc --noEmit exits clean. No test files were modified and no dependencies were added.

Bugs fixed

Package	File	Fix
root	bunfig.toml	environment = "happy-dom" is not a valid Bun key (silently ignored → document is not defined in React component tests). Switched to preload of the happy-dom setup so the DOM is registered.
utils	packages/utils/src/format/date.ts	formatDate zero-padded single-digit days (01/03/2024). Test expects day-first 1/03/2024. en-AU resolves day: 'numeric' to 2-digit; en-GB honours it — now emits unpadded day, 2-digit month, 4-digit year.
web	apps/web/src/lib/api.ts	useThrottle was renamed to useDebounce in @e2e/utils. Updated the import, usage and the useSearchDebounce re-export.
ui	packages/ui/src/components/Button/Button.tsx	Icon-only buttons had no aria-label. Now passes an explicit label through, falling back to a meaningful name derived from string children before a last-resort literal.
ui	packages/ui/src/components/DataTable/DataTable.tsx	Sort-direction toggle read sortDir from the render closure. Switched to the functional setSortDir(prev => ...) form.
root	tsconfig.json	Added "types": ["bun-types"] so bun:test imports resolve under tsc.

Verification

• bun test → 13 pass / 0 fail
• tsc --noEmit → exit 0
• No test files changed; no dependencies added.

Assumptions & notes

• aria-label for icon-only buttons: the test only asserts a non-null label. The sound long-term fix is a discriminated union making aria-label mandatory when iconOnly is true, but that would require changing the test, so it's out of scope here. This PR derives a meaningful name from children where possible and keeps a "button" literal only as a last resort. Worth a follow-up ticket.
• en-GB locale in formatDate: produces byte-identical output to an en-AU + zero-strip approach on tested dates while keeping the 4-digit year. Flagged as a latent trap if weekday/month: 'long' are later added. formatDateTime untouched.
• bun-types at root scope: minimal change that makes bun:test resolve; scoping it to test files via a dedicated tsconfig is a reasonable follow-up.
• DataTable functional setState: correct best-practice for a toggle derived from prior state; docblock updated to remove an inaccurate failure-mode description.

🤖 Generated autonomously.