Complete Phase 2: Frontend implementation with React + TypeScript

Frontend Features:
- React 18 + Vite + TypeScript + Tailwind CSS + Zustand
- JWT authentication with automatic token refresh
- Tree library with search and category filtering
- Full tree navigation (decision/action/solution nodes)
- Session management with notes and completion
- Session history with export (Markdown/Text/HTML)
- ErrorBoundary for graceful error handling

Backend Fixes:
- CORS: Added port 5174 to allowed origins
- Sessions: Fixed JSONB datetime serialization (mode='json')

Documentation:
- Updated PROGRESS.md with Phase 2 completion
- Updated 03-DEVELOPMENT-ROADMAP.md with checked items
- Added PHASE-2.5-PERSONAL-BRANCHING.md spec

Seed Data:
- Added backend/scripts/seed_data.py with Password Reset tree

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/components/layout/ProtectedRoute.tsx

@@ -0,0 +1,27 @@
+import { Navigate, useLocation } from 'react-router-dom'
+import { useAuthStore } from '@/store/authStore'
+
+interface ProtectedRouteProps {
+  children: React.ReactNode
+}
+
+export function ProtectedRoute({ children }: ProtectedRouteProps) {
+  const { isAuthenticated, isLoading } = useAuthStore()
+  const location = useLocation()
+
+  if (isLoading) {
+    return (
+      <div className="flex h-screen items-center justify-center">
+        <div className="h-8 w-8 animate-spin rounded-full border-4 border-primary border-t-transparent" />
+      </div>
+    )
+  }
+
+  if (!isAuthenticated) {
+    return <Navigate to="/login" state={{ from: location }} replace />
+  }
+
+  return <>{children}</>
+}
+
+export default ProtectedRoute