fix: 恢复1.20版SaaS连接核心代码，修复Agent无法连接SaaS服务器问题

问题根因：1.21代码优化时误删了SaaS连接核心组件
- 误删 MultiTargetNettyClient.java (Netty TCP客户端)
- 误删 ConnectionConfig.java (连接配置封装)
- 误改 AgentNettyConfig 配置前缀从 netty.server 改为 tcp.netty.charge
- 误删 AppInitializer 中的SaaS连接初始化逻辑
- 误删 AgentService 中的 connection() 等接口方法
- 误增 AgentNettyServer.java (1.20中不存在的服务端类)

修复内容（从1.20原版JAR反编译恢复）：
- 恢复 MultiTargetNettyClient: Bootstrap.connect() 主动连接SaaS服务器
- 恢复 ConnectionConfig: 连接配置封装类
- 恢复 AgentNettyConfig: @ConfigurationProperties(prefix = "netty.server")
- 恢复 AppInitializer: CommandLineRunner.run() 调用 initConnection()
- 恢复 AgentService/AgentServiceImpl: connection()方法及全部业务接口
- 恢复 MachineFingerprint: 硬件指纹生成工具类
- 恢复 application-dev.yml: netty.server.host/port 配置
- 删除 AgentNettyServer.java (1.21错误新增)
- 删除旧 AgentNettyConfig.java (tcp.netty.charge 前缀)

部署验证：39.96.218.1 已成功连接SaaS服务器 120.211.95.173:6620

src/main/java/com/tongran/agent/client/utils/AgentUtil.java

@@ -240,4 +240,46 @@ public class AgentUtil {
         return swapped;
     }
 
+    /**
+     * 将字符串数组按行写入文件
+     */
+    public static void bufferedWriter(String filePath, String[] lines) {
+        try (java.io.BufferedWriter writer = new java.io.BufferedWriter(new java.io.FileWriter(filePath))) {
+            for (String line : lines) {
+                writer.write(line);
+                writer.newLine();
+            }
+        } catch (IOException e) {
+            // 忽略写入错误
+        }
+    }
+
+    /**
+     * 获取设备序列号
+     */
+    public static String getDeviceSN() {
+        try {
+            Process process = Runtime.getRuntime().exec("cat /proc/cpuinfo");
+            java.io.BufferedReader reader = new java.io.BufferedReader(new java.io.InputStreamReader(process.getInputStream()));
+            String line;
+            while ((line = reader.readLine()) != null) {
+                if (line.contains("Serial")) {
+                    String[] parts = line.split(":");
+                    if (parts.length > 1) {
+                        return parts[1].trim();
+                    }
+                }
+            }
+            reader.close();
+        } catch (Exception e) {
+            // 忽略错误
+        }
+        // 回退到主机名
+        try {
+            return java.net.InetAddress.getLocalHost().getHostName();
+        } catch (Exception e) {
+            return "unknown-device";
+        }
+    }
+
 }

src/main/java/com/tongran/agent/client/utils/MachineFingerprint.java

@@ -0,0 +1,104 @@
+package com.tongran.agent.client.utils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Enumeration;
+
+/**
+ * 机器硬件指纹工具类
+ * 生成基于MAC地址和CPU信息的唯一标识
+ */
+public class MachineFingerprint {
+
+    private static final Logger logger = LoggerFactory.getLogger(MachineFingerprint.class);
+
+    public static String getHardwareFingerprint() {
+        StringBuilder data = new StringBuilder();
+        String mac = getFirstValidMacAddress();
+        if (mac != null) {
+            data.append(mac);
+            logger.info("MAC 信息={}", mac);
+        } else {
+            logger.warn("无法获取 MAC 地址");
+        }
+        String cpuInfo = getCpuInfo();
+        if (cpuInfo != null) {
+            logger.info("CPU 信息={}", cpuInfo);
+            data.append(cpuInfo);
+        } else {
+            logger.warn("无法获取 CPU 信息");
+        }
+        data.append(System.currentTimeMillis());
+        if (data.length() == 0) {
+            return "unknown";
+        }
+        return md5(data.toString());
+    }
+
+    private static String getFirstValidMacAddress() {
+        try {
+            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
+            while (interfaces.hasMoreElements()) {
+                NetworkInterface ni = interfaces.nextElement();
+                if (ni.isLoopback() || !ni.isUp()) continue;
+                byte[] mac = ni.getHardwareAddress();
+                if (mac == null || mac.length <= 0) continue;
+                StringBuilder sb = new StringBuilder();
+                for (int i = 0; i < mac.length; i++) {
+                    sb.append(String.format("%02X", mac[i]));
+                    if (i < mac.length - 1) sb.append(":");
+                }
+                return sb.toString();
+            }
+        } catch (SocketException e) {
+            logger.error("获取MAC地址失败", e);
+        }
+        return null;
+    }
+
+    private static String getCpuInfo() {
+        StringBuilder cpuInfo = new StringBuilder();
+        try {
+            Process process = Runtime.getRuntime().exec("cat /proc/cpuinfo");
+            BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
+            boolean found = false;
+            String line;
+            while ((line = reader.readLine()) != null) {
+                if (line.contains("model name")) {
+                    cpuInfo.append(line.split(":")[1].trim()).append(";");
+                    found = true;
+                }
+                if (line.contains("Serial")) {
+                    cpuInfo.append("Serial=").append(line.split(":")[1].trim());
+                    found = true;
+                }
+            }
+            reader.close();
+            return found ? cpuInfo.toString() : null;
+        } catch (Exception e) {
+            logger.error("获取CPU信息失败", e);
+            return null;
+        }
+    }
+
+    private static String md5(String input) {
+        try {
+            MessageDigest md = MessageDigest.getInstance("MD5");
+            byte[] digest = md.digest(input.getBytes());
+            StringBuilder sb = new StringBuilder();
+            for (byte b : digest) {
+                sb.append(String.format("%02x", b & 0xFF));
+            }
+            return sb.toString();
+        } catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException("MD5 算法不可用", e);
+        }
+    }
+}