Add Claude API support and fix CORS issues

- Add Claude API integration to LLM service
- Create Express backend server with CORS support
- Add API proxy example page
- Fix CORS errors by routing through backend
- Update LLM configuration to support Claude
- Add package.json with dependencies

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

server.js

@@ -0,0 +1,151 @@
+/**
+ * Express Server
+ * HR 績效評核系統後端伺服器
+ */
+
+require('dotenv').config();
+const express = require('express');
+const cors = require('cors');
+const helmet = require('helmet');
+const morgan = require('morgan');
+const path = require('path');
+
+// Import routes
+const llmRoutes = require('./routes/llm.routes');
+
+// Import error handler
+const { handleError } = require('./utils/errorHandler');
+
+// Create Express app
+const app = express();
+const PORT = process.env.PORT || 3000;
+
+// ============================================
+// Middleware
+// ============================================
+
+// Security headers
+app.use(helmet());
+
+// CORS configuration
+app.use(cors({
+  origin: process.env.FRONTEND_URL || '*',
+  methods: ['GET', 'POST', 'PUT', 'DELETE', 'PATCH'],
+  allowedHeaders: ['Content-Type', 'Authorization'],
+  credentials: true,
+}));
+
+// Body parsing
+app.use(express.json({ limit: '10mb' }));
+app.use(express.urlencoded({ extended: true, limit: '10mb' }));
+
+// Logging
+if (process.env.NODE_ENV === 'development') {
+  app.use(morgan('dev'));
+} else {
+  app.use(morgan('combined'));
+}
+
+// Static files
+app.use(express.static('public'));
+
+// ============================================
+// Routes
+// ============================================
+
+// Health check
+app.get('/health', (req, res) => {
+  res.json({
+    success: true,
+    message: 'HR Performance System API is running',
+    timestamp: new Date().toISOString(),
+    environment: process.env.NODE_ENV,
+  });
+});
+
+// API routes
+app.use('/api/llm', llmRoutes);
+
+// Root endpoint
+app.get('/', (req, res) => {
+  res.json({
+    name: 'HR Performance System API',
+    version: '1.0.0',
+    description: '四卡循環績效管理系統',
+    endpoints: {
+      health: '/health',
+      llm: '/api/llm',
+    },
+  });
+});
+
+// ============================================
+// Error Handling
+// ============================================
+
+// 404 handler
+app.use((req, res, next) => {
+  res.status(404).json({
+    success: false,
+    error: {
+      statusCode: 404,
+      message: `Cannot ${req.method} ${req.path}`,
+      timestamp: new Date().toISOString(),
+      path: req.path,
+    },
+  });
+});
+
+// Global error handler
+app.use(handleError);
+
+// ============================================
+// Server Start
+// ============================================
+
+const server = app.listen(PORT, () => {
+  console.log('='.repeat(50));
+  console.log('🚀 HR Performance System API Server');
+  console.log('='.repeat(50));
+  console.log(`📡 Server running on: http://localhost:${PORT}`);
+  console.log(`🌍 Environment: ${process.env.NODE_ENV || 'development'}`);
+  console.log(`📅 Started at: ${new Date().toLocaleString('zh-TW')}`);
+  console.log('='.repeat(50));
+  console.log('\n📚 Available endpoints:');
+  console.log(`   GET  /               - API information`);
+  console.log(`   GET  /health         - Health check`);
+  console.log(`   POST /api/llm/test/* - Test LLM connections`);
+  console.log(`   POST /api/llm/generate - Generate content with LLM`);
+  console.log('\n✨ Server is ready to accept connections!\n');
+});
+
+// Graceful shutdown
+process.on('SIGTERM', () => {
+  console.log('\n⚠️  SIGTERM received. Shutting down gracefully...');
+  server.close(() => {
+    console.log('✅ Server closed');
+    process.exit(0);
+  });
+});
+
+process.on('SIGINT', () => {
+  console.log('\n⚠️  SIGINT received. Shutting down gracefully...');
+  server.close(() => {
+    console.log('✅ Server closed');
+    process.exit(0);
+  });
+});
+
+// Uncaught exception handler
+process.on('uncaughtException', (error) => {
+  console.error('❌ Uncaught Exception:', error);
+  process.exit(1);
+});
+
+// Unhandled rejection handler
+process.on('unhandledRejection', (reason, promise) => {
+  console.error('❌ Unhandled Rejection at:', promise, 'reason:', reason);
+  process.exit(1);
+});
+
+module.exports = app;