fix: resolve failing tests and type errors across monorepo - #294

Fixes failing tests and type errors across ui, utils and web.

• apps/web api.ts: use renamed useDebounce instead of useThrottle
• utils date.ts: en-AU D/MM/YYYY via formatToParts (direct formatting zero-pads the day)
• ui Button: forward aria-label; icon-only fallback "Button" + dev warning
• ui DataTable: functional setState for sort toggle
• bunfig.toml: preload happy-dom setup (invalid environment key removed)
• tsconfig: types bun-types (already installed)

Verification: bun test 13/13 pass; bunx tsc --noEmit clean.
Assumptions: tsc not on PATH so used bunx; no test files modified; no deps added.