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/sessions.ts

@@ -0,0 +1,51 @@
+import apiClient from './client'
+import type { Session, SessionCreate, SessionUpdate, SessionExport } from '@/types'
+
+export interface SessionListParams {
+  page?: number
+  size?: number
+  tree_id?: string
+  completed?: boolean
+}
+
+export interface SessionListResponse {
+  items: Session[]
+  total: number
+  page: number
+  size: number
+  pages: number
+}
+
+export const sessionsApi = {
+  async list(params?: SessionListParams): Promise<Session[]> {
+    const response = await apiClient.get<Session[]>('/sessions', { params })
+    return response.data
+  },
+
+  async get(id: string): Promise<Session> {
+    const response = await apiClient.get<Session>(`/sessions/${id}`)
+    return response.data
+  },
+
+  async create(data: SessionCreate): Promise<Session> {
+    const response = await apiClient.post<Session>('/sessions', data)
+    return response.data
+  },
+
+  async update(id: string, data: SessionUpdate): Promise<Session> {
+    const response = await apiClient.put<Session>(`/sessions/${id}`, data)
+    return response.data
+  },
+
+  async complete(id: string): Promise<Session> {
+    const response = await apiClient.post<Session>(`/sessions/${id}/complete`)
+    return response.data
+  },
+
+  async export(id: string, options: SessionExport): Promise<string> {
+    const response = await apiClient.post<string>(`/sessions/${id}/export`, options)
+    return response.data
+  },
+}
+
+export default sessionsApi