fix: repair cross-package bugs to make test suite pass

[stooit]

Summary

Fixes all failing tests and type errors across the monorepo. bun test (13 pass / 0 fail) and tsc --noEmit (clean) now both succeed from the repo root.

The bugs spanned all three packages plus the test-environment config.

Changes

File	Bug	Fix
apps/web/src/lib/api.ts	Imported the old hook name useThrottle after it was renamed to useDebounce in @e2e/utils	Import/re-export useDebounce (still surfaced as useSearchDebounce)
packages/ui/src/components/Button/Button.tsx	ariaLabel prop destructured but never applied	Forward aria-label to the rendered <button>
packages/ui/src/components/DataTable/DataTable.tsx	Stale-closure bug — sort toggle read sortDir from the closure	Use functional updater setSortDir(prev => ...)
packages/utils/src/format/date.ts	Explicit month/day/year options forced US MM/DD/YYYY, overriding en-AU	Use { dateStyle: 'short' } so en-AU yields day-first DD/MM/YYYY
packages/ui/bunfig.toml	Package-local bunfig lacked happy-dom env → document is not defined	Add environment = "happy-dom" (keep preload)
bunfig.toml	Root test env needed matching preload/env for component tests	Aligned test config
tsconfig.json	tsc could not resolve bun:test globals	Register bun-types

Verification

• bun test → 13 pass, 0 fail
• tsc --noEmit → clean (exit 0)

Assumptions

• The hook rename useThrottle → useDebounce is the intended source name; the public alias useSearchDebounce (asserted by tests) is preserved.
• The two config files were treated as legitimate non-test config fixes — only the test environment was repaired; no test files modified, no dependencies added.

Constraints honoured

• No test files modified.
• No dependencies added.