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/router.tsx

@@ -0,0 +1,57 @@
+import { createBrowserRouter, Navigate } from 'react-router-dom'
+import { AppLayout, ProtectedRoute } from '@/components/layout'
+import { RouteError } from '@/components/common/RouteError'
+import {
+  LoginPage,
+  RegisterPage,
+  TreeLibraryPage,
+  TreeNavigationPage,
+  SessionHistoryPage,
+  SessionDetailPage,
+} from '@/pages'
+
+export const router = createBrowserRouter([
+  {
+    path: '/login',
+    element: <LoginPage />,
+    errorElement: <RouteError />,
+  },
+  {
+    path: '/register',
+    element: <RegisterPage />,
+    errorElement: <RouteError />,
+  },
+  {
+    path: '/',
+    element: (
+      <ProtectedRoute>
+        <AppLayout />
+      </ProtectedRoute>
+    ),
+    errorElement: <RouteError />,
+    children: [
+      {
+        index: true,
+        element: <Navigate to="/trees" replace />,
+      },
+      {
+        path: 'trees',
+        element: <TreeLibraryPage />,
+      },
+      {
+        path: 'trees/:id/navigate',
+        element: <TreeNavigationPage />,
+      },
+      {
+        path: 'sessions',
+        element: <SessionHistoryPage />,
+      },
+      {
+        path: 'sessions/:id',
+        element: <SessionDetailPage />,
+      },
+    ],
+  },
+])
+
+export default router