v2.0.0: Multi-user authentication with JWT

Features:
- User registration and login with JWT tokens
- All data is now user-specific (multi-tenancy)
- Profile page with integrations and logout
- Automatic migration of existing data to first user

Backend changes:
- Added users and refresh_tokens tables
- Added user_id to all data tables (projects, entries, nodes, dictionaries, words, progress, configs, telegram_integrations, weekly_goals)
- JWT authentication middleware
- claimOrphanedData() for data migration

Frontend changes:
- AuthContext for state management
- Login/Register forms
- Profile page (replaced Integrations)
- All API calls use authFetch with Bearer token

Migration notes:
- On first deploy, backend automatically adds user_id columns
- First user to login claims all existing data

play-life-web/src/components/TelegramIntegration.jsx

@@ -1,7 +1,9 @@
 import React, { useState, useEffect } from 'react'
+import { useAuth } from './auth/AuthContext'
 import './Integrations.css'
 
 function TelegramIntegration({ onBack }) {
+  const { authFetch } = useAuth()
   const [botToken, setBotToken] = useState('')
   const [chatId, setChatId] = useState('')
   const [loading, setLoading] = useState(true)
@@ -16,7 +18,7 @@ function TelegramIntegration({ onBack }) {
   const fetchIntegration = async () => {
     try {
       setLoading(true)
-      const response = await fetch('/api/integrations/telegram')
+      const response = await authFetch('/api/integrations/telegram')
       if (!response.ok) {
         throw new Error('Ошибка при загрузке интеграции')
       }
@@ -42,7 +44,7 @@ function TelegramIntegration({ onBack }) {
       setError('')
       setSuccess('')
 
-      const response = await fetch('/api/integrations/telegram', {
+      const response = await authFetch('/api/integrations/telegram', {
         method: 'POST',
         headers: {
           'Content-Type': 'application/json',