feat: self-serve signup Phase 2 (frontend cutover) (#162)

Co-authored-by: Michael Chihlas <michael@resolutionflow.com>
Co-committed-by: Michael Chihlas <michael@resolutionflow.com>

frontend/src/pages/welcome/WelcomeRouter.tsx

@@ -0,0 +1,31 @@
+import { Navigate } from 'react-router-dom'
+import { useAuthStore } from '@/store/authStore'
+import { PageLoader } from '@/components/common/PageLoader'
+
+/**
+ * `/welcome` index — redirect to the next incomplete step (or `/` if done /
+ * dismissed). Decision table:
+ *
+ *   onboarding_dismissed === true            → /
+ *   onboarding_step_completed >= 3           → /
+ *   onboarding_step_completed === null/0     → /welcome/step-1
+ *   onboarding_step_completed === 1          → /welcome/step-2
+ *   onboarding_step_completed === 2          → /welcome/step-3
+ */
+export function WelcomeRouter() {
+  const user = useAuthStore((s) => s.user)
+
+  // Auth gate sits above us — but if the user object is still loading, render
+  // the page loader rather than racing past the redirect.
+  if (!user) return <PageLoader />
+
+  if (user.onboarding_dismissed) return <Navigate to="/" replace />
+
+  const completed = user.onboarding_step_completed ?? 0
+  if (completed >= 3) return <Navigate to="/" replace />
+  if (completed === 2) return <Navigate to="/welcome/step-3" replace />
+  if (completed === 1) return <Navigate to="/welcome/step-2" replace />
+  return <Navigate to="/welcome/step-1" replace />
+}
+
+export default WelcomeRouter