frontend: keep app shell visible during auth loading

Author: owenisas

frontend/src/components/app/AppShell.tsx

@@ -68,8 +68,8 @@ function AuthGate({ children }: { children: React.ReactNode }) {
   )
 
   if (user) return <>{children}</>
-  // First visit auth loading.
-  if (loading) return renderGateStatus("Checking your session...")
+  // Keep existing shell visible during transient auth loading (prevents sidebar flicker/disappear).
+  if (loading) return <>{children}</>
   // Not authenticated, redirecting away from dashboard.
   if (!user) return renderGateStatus("Redirecting to sign-in...")
   return <>{children}</>