fix: repair failing tests and type errors across monorepo

[stooit]

Summary

Fixes all failing tests and type errors so bun test && tsc --noEmit passes cleanly (13 pass / 0 fail, tsc exit 0; baseline was 4 pass / 9 fail with 6 type errors). Bugs spanned all three packages.

Fixes

• apps/web/src/lib/api.ts — the useThrottle hook was renamed in packages/utils (now useDebounce); updated the stale import and usage. (Resolves TS2305: Module '@e2e/utils' has no exported member 'useThrottle'.)
• packages/ui/src/components/Button/Button.tsx — added the required aria-label for iconOnly buttons (WCAG 2.2 SC 4.1.2), asserted by the Button test.
• packages/ui/src/components/DataTable/DataTable.tsx — fixed a stale-closure bug in the sort toggle (functional state updater) so "sorts descending on second click" passes under controlled re-render.
• packages/utils/src/format/date.ts — corrected date formatting to produce a non-padded day so 2024-03-01 renders as 1/03/2024.

Test-environment / config fixes (no test files modified, no deps added)

• bunfig.toml — replaced an inert environment setting with a preload of the existing DOM setup script, resolving ReferenceError: document is not defined from @testing-library/react's render().
• tsconfig.json — added bun-types to compilerOptions.types (already in node_modules) to resolve Cannot find module 'bun:test'.

Constraints honoured

• No test files modified. No new dependencies added. Only changes required by the failing tests/type errors.

Assumptions

• The bunfig.toml preload of the pre-existing UI test setup script is the intended DOM wiring.
• useDebounce is the correct, signature-compatible replacement for the renamed useThrottle at the api.ts call site.