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>

package.json

@@ -0,0 +1,40 @@
+{
+  "name": "hr-performance-system",
+  "version": "1.0.0",
+  "description": "HR 績效評核系統 - 四卡循環管理平台",
+  "main": "server.js",
+  "scripts": {
+    "start": "node server.js",
+    "dev": "nodemon server.js",
+    "test": "jest",
+    "lint": "eslint .",
+    "format": "prettier --write \"**/*.{js,jsx,json,md}\""
+  },
+  "keywords": [
+    "hr",
+    "performance",
+    "management",
+    "four-card-system"
+  ],
+  "author": "Donald",
+  "license": "ISC",
+  "dependencies": {
+    "axios": "^1.6.2",
+    "cors": "^2.8.5",
+    "dotenv": "^16.3.1",
+    "express": "^4.18.2",
+    "helmet": "^7.1.0",
+    "morgan": "^1.10.0",
+    "mysql2": "^3.6.5"
+  },
+  "devDependencies": {
+    "nodemon": "^3.0.2",
+    "eslint": "^8.55.0",
+    "prettier": "^3.1.1",
+    "jest": "^29.7.0"
+  },
+  "engines": {
+    "node": ">=16.0.0",
+    "npm": ">=8.0.0"
+  }
+}