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/api/client.ts

@@ -0,0 +1,66 @@
+import axios, { type AxiosError, type InternalAxiosRequestConfig } from 'axios'
+
+const API_BASE_URL = import.meta.env.VITE_API_URL || 'http://localhost:8000'
+
+export const apiClient = axios.create({
+  baseURL: `${API_BASE_URL}/api/v1`,
+  headers: {
+    'Content-Type': 'application/json',
+  },
+})
+
+// Request interceptor - add auth token
+apiClient.interceptors.request.use(
+  (config: InternalAxiosRequestConfig) => {
+    const token = localStorage.getItem('access_token')
+    if (token && config.headers) {
+      config.headers.Authorization = `Bearer ${token}`
+    }
+    return config
+  },
+  (error) => Promise.reject(error)
+)
+
+// Response interceptor - handle token refresh
+apiClient.interceptors.response.use(
+  (response) => response,
+  async (error: AxiosError) => {
+    const originalRequest = error.config as InternalAxiosRequestConfig & { _retry?: boolean }
+
+    // If 401 and not already retrying, attempt token refresh
+    if (error.response?.status === 401 && !originalRequest._retry) {
+      originalRequest._retry = true
+
+      const refreshToken = localStorage.getItem('refresh_token')
+      if (refreshToken) {
+        try {
+          const response = await axios.post(`${API_BASE_URL}/api/v1/auth/refresh`, null, {
+            headers: {
+              Authorization: `Bearer ${refreshToken}`,
+            },
+          })
+
+          const { access_token, refresh_token } = response.data
+          localStorage.setItem('access_token', access_token)
+          localStorage.setItem('refresh_token', refresh_token)
+
+          // Retry original request with new token
+          if (originalRequest.headers) {
+            originalRequest.headers.Authorization = `Bearer ${access_token}`
+          }
+          return apiClient(originalRequest)
+        } catch (refreshError) {
+          // Refresh failed - clear tokens and redirect to login
+          localStorage.removeItem('access_token')
+          localStorage.removeItem('refresh_token')
+          window.location.href = '/login'
+          return Promise.reject(refreshError)
+        }
+      }
+    }
+
+    return Promise.reject(error)
+  }
+)
+
+export default apiClient