feat(mobile): AppBootstrap boundary — defers crypto init, catches global throws

apps/mobile/components/AppBootstrap.tsx

@@ -0,0 +1,51 @@
+import { crypto } from '@chat-app/shared';
+import { type ReactNode, useEffect, useState } from 'react';
+
+import { createLibsodiumBackend } from '../lib/cryptoBackend';
+import { BootError } from './BootError';
+import { BootSplash } from './BootSplash';
+
+interface Props {
+  children: ReactNode;
+}
+
+// React Native exposes ErrorUtils on the global. The types ship with RN but
+// we cast defensively because the renderer used by Vitest does not.
+interface RNErrorUtils {
+  getGlobalHandler: () => (err: Error, isFatal?: boolean) => void;
+  setGlobalHandler: (handler: (err: Error, isFatal?: boolean) => void) => void;
+}
+
+// Initialises the crypto backend inside a useEffect (not at module-eval) so
+// any failure surfaces in the React tree. Also installs a global JS error
+// handler that routes unhandled throws to BootError; this catches errors
+// thrown during render (e.g. the lazy env proxy reading a missing var) that
+// would otherwise escape every per-screen ErrorBoundary.
+export function AppBootstrap({ children }: Props) {
+  const [error, setError] = useState<Error | null>(null);
+  const [ready, setReady] = useState(false);
+
+  useEffect(() => {
+    try {
+      crypto.setCryptoBackend(createLibsodiumBackend());
+      setReady(true);
+    } catch (e: unknown) {
+      setError(e instanceof Error ? e : new Error(String(e)));
+    }
+  }, []);
+
+  useEffect(() => {
+    const eu = (globalThis as unknown as { ErrorUtils?: RNErrorUtils }).ErrorUtils;
+    if (!eu) return;
+    const prev = eu.getGlobalHandler();
+    eu.setGlobalHandler((err, isFatal) => {
+      prev?.(err, isFatal);
+      setError(err);
+    });
+    return () => eu.setGlobalHandler(prev);
+  }, []);
+
+  if (error) return <BootError error={error} />;
+  if (!ready) return <BootSplash />;
+  return <>{children}</>;
+}