feat: 实现仪表盘页面及系统信息采集功能

新增系统信息采集后端服务，引入 sysinfo 依赖获取 CPU、内存、主机名、系统版本、架构和 IP 地址等数据；新增系统相关 API 接口和 TypeScript 类型定义；重构仪表盘页面，整合服务器/隧道数量统计、系统信息展示、资源占用监控和 Frpc 运行日志功能；新增中英文国际化文案支持，完善前端交互逻辑。

src/i18n/locales/en-US.json

@@ -33,6 +33,24 @@
     "statusError": "Error",
     "statusStopped": "Stopped"
   },
+  "dashboard": {
+    "serverCount": "Servers",
+    "tunnelCount": "Tunnels",
+    "hostname": "Hostname",
+    "os": "OS",
+    "arch": "Architecture",
+    "ip": "IP address",
+    "frpcVersion": "Frpc version",
+    "start": "One-click start",
+    "stop": "Stop",
+    "logs": "Live logs",
+    "clear": "Clear",
+    "mock": "Mock data",
+    "logEmpty": "No logs yet. Live logs will appear here once Frpc starts.",
+    "logReady": "Frpilot is ready. Waiting for Frpc to start.",
+    "logStarted": "Frpc {version} started",
+    "logStopped": "Frpc stopped"
+  },
   "settings": {
     "title": "Settings",
     "placeholder": "The settings page is under construction.",