fix: resolve failing tests and type errors across monorepo

[stooit]

Makes bun test && tsc --noEmit pass (13/13, tsc clean). No test changes, no new deps.

• utils formatDate: day-first en-AU, no leading zero on day, 4-digit year.
• web api.ts: import renamed hook useDebounce (stale useThrottle); useSearchDebounce re-export kept.
• ui Button: apply aria-label to icon-only buttons (fallback + dev warning).
• ui DataTable: fix stale closure in sort toggle (functional setSortDir).
• bunfig.toml: replace unsupported environment key with preload of existing happy-dom setup.
• tsconfig.json: add types bun-types (existing devDep) and DOM libs.

Assumptions: useThrottle->useDebounce was an intentional rename; a generic fallback aria-label is acceptable for the unlabeled test case.
Out of scope: DataTable th not keyboard operable; formatDateTime 2-digit year.