feat: 实现许可证激活和验证功能，增加许可证管理服务器

server/models/License.js

@@ -0,0 +1,28 @@
+const mongoose = require('mongoose');
+
+const licenseSchema = new mongoose.Schema({
+    licenseKey: {
+        type: String,
+        required: true,
+        unique: true
+    },
+    machineCode: {
+        type: String,
+        required: true
+    },
+    activationDate: {
+        type: Date,
+        required: true,
+        default: Date.now
+    },
+    expiryDate: {
+        type: Date,
+        required: true
+    },
+    isActive: {
+        type: Boolean,
+        default: true
+    }
+});
+
+module.exports = mongoose.model('License', licenseSchema);