`crypto.randomUUID` only exists in secure contexts (HTTPS or localhost).
Over LAN HTTP it is undefined, so `ChatPane`'s welcome-message flush and
streaming-message handlers crash mid-render with `TypeError`, unmounting
the React tree and leaving the user a blank page.
Install a Math.random-backed v4-ish fallback at app entry, gated on the
feature being missing. This mirrors the shim already used in the test
setup and covers all six call sites (`ChatPane.tsx`, `useNanobotStream.ts`)
without touching them. These IDs are client-side message keys with no
security role, so non-cryptographic randomness is fine.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
