[app-bug] No top-level error boundary — unhandled React errors blank the whole app

[Gbangbolaoluwagbemiga]

Problem

ErrorBoundary.tsx exists and is used in a couple of leaf components, but the app root has no boundary. An unhandled error in WorkspaceProvider, WorkspaceSidebar, or any page becomes a blank white screen with no recovery action.

Acceptance Criteria

• Wrap the children inside RootLayout with the existing ErrorBoundary
• Friendly fallback UI: title, short message, Reload button, Copy details button (so users can paste into an issue)
• Same treatment for Next.js' app-router error.tsx per route segment

Pointers

• frontend/app/layout.tsx
• frontend/app/components/ErrorBoundary.tsx
• frontend/app/error.tsx

Difficulty

Easy. A few wrappings + a polished fallback.