Fix crypto.randomUUID crash on non-HTTPS origins

Replace all crypto.randomUUID() calls with a uuid() utility that
falls back to Math.random-based generation when the Web Crypto API
is unavailable (plain HTTP contexts).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/shared/src/utils/formatting.ts

@@ -24,6 +24,16 @@ export function formatFlops(n: number): string {
   return `${formatNumber(n)} FLOPS`;
 }
 
+export function uuid(): string {
+  if (typeof crypto !== 'undefined' && crypto.randomUUID) {
+    return crypto.randomUUID();
+  }
+  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
+    const r = (Math.random() * 16) | 0;
+    return (c === 'x' ? r : (r & 0x3) | 0x8).toString(16);
+  });
+}
+
 export function formatDuration(ticks: number): string {
   if (ticks < 60) return `${ticks}s`;
   if (ticks < 3600) return `${Math.floor(ticks / 60)}m ${ticks % 60}s`;