feat: add monitoring agent (Go) + agent report API + cloud billing UI

- Go agent: CPU/mem/disk/port collectors, HTTP report, static binary
- Cross-compile: linux/amd64 + linux/arm64 (statically linked)
- One-line install script for all Linux distros
- Backend: POST /api/v1/agent/report (no JWT) + GET /agent/latest,history (JWT)
- CloudBilling.tsx: fixed syntax errors, stats/trends/records/alerts
- K8s menu renamed to Kubernetes管理

Signed-off-by: Logan.Li

agent/main.go

@@ -0,0 +1,136 @@
+// Package main 是 AIOps Agent 的入口。
+// Agent 定时采集 CPU、内存、磁盘及监听端口指标，并通过 HTTP 上报至 AIOps 后端。
+//
+// 以下变量可在编译时通过 -ldflags "-X main.version=... -X main.buildTime=..." 注入。
+//
+// 署名 Logan.Li
+package main
+
+import (
+	"context"
+	"flag"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"ezops/agent/collector"
+	"ezops/agent/model"
+	"ezops/agent/reporter"
+)
+
+// 编译时可注入的版本信息
+var (
+	version   = "dev"
+	buildTime = "unknown"
+)
+
+func main() {
+	server := flag.String("server", "http://localhost:8080", "AIOps 后端上报地址（含 scheme 与端口）")
+	interval := flag.Int("interval", 10, "采集与上报间隔，单位：秒")
+	token := flag.String("token", "", "Bearer 鉴权令牌")
+	hostnameFlag := flag.String("hostname", "", "上报主机名，默认使用系统主机名")
+	flag.Parse()
+
+	// 统一日志格式：带微秒时间戳，便于排查问题
+	logger := log.New(os.Stdout, "[aiops-agent] ", log.LstdFlags|log.Lmicroseconds)
+
+	// 解析主机名：优先使用 -hostname，否则回退到 os.Hostname()
+	hostname := *hostnameFlag
+	if hostname == "" {
+		if h, err := os.Hostname(); err == nil {
+			hostname = h
+		} else {
+			hostname = "unknown"
+		}
+	}
+
+	// 参数校验
+	if *server == "" {
+		logger.Fatal("参数 -server 不能为空")
+	}
+	if *interval < 1 {
+		logger.Fatalf("参数 -interval 必须 >= 1，当前为 %d", *interval)
+	}
+
+	logger.Printf("AIOps Agent 启动: version=%s buildTime=%s", version, buildTime)
+	logger.Printf("配置: server=%s interval=%ds hostname=%q token=%s",
+		*server, *interval, hostname, maskToken(*token))
+
+	// 初始化各采集器与上报器
+	cpuCollector := collector.NewCPUCollector()
+	memCollector := collector.NewMemCollector()
+	diskCollector := collector.NewDiskCollector()
+	portCollector := collector.NewPortCollector()
+	rep := reporter.New(*server, *token, logger)
+
+	// 监听 SIGINT / SIGTERM，支持优雅退出
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
+
+	ticker := time.NewTicker(time.Duration(*interval) * time.Second)
+	defer ticker.Stop()
+
+	// collectAndReport 执行单次采集并上报；各项采集独立进行，单项失败不影响整体上报
+	collectAndReport := func() {
+		report := &model.Report{
+			Hostname:  hostname,
+			Timestamp: time.Now().UTC().Format(time.RFC3339),
+		}
+
+		if stat, err := cpuCollector.Collect(); err != nil {
+			logger.Printf("CPU 采集异常: %v", err)
+		} else {
+			report.CPU = stat
+		}
+
+		if stat, err := memCollector.Collect(); err != nil {
+			logger.Printf("内存采集异常: %v", err)
+		} else {
+			report.Memory = stat
+		}
+
+		if disks, err := diskCollector.Collect(); err != nil {
+			logger.Printf("磁盘采集异常: %v", err)
+		} else {
+			report.Disks = disks
+		}
+
+		if ports, err := portCollector.Collect(); err != nil {
+			logger.Printf("端口采集异常: %v", err)
+		} else {
+			report.Ports = ports
+		}
+
+		if err := rep.Send(ctx, report); err != nil {
+			logger.Printf("上报失败: %v", err)
+			return
+		}
+		logger.Printf("上报成功: cpu=%.2f%% mem=%.2f%% disks=%d ports=%d",
+			report.CPU.UsagePercent, report.Memory.UsagePercent, len(report.Disks), len(report.Ports))
+	}
+
+	// 启动后立即执行一次，再按 ticker 周期执行
+	collectAndReport()
+	for {
+		select {
+		case <-ticker.C:
+			collectAndReport()
+		case <-ctx.Done():
+			logger.Println("收到退出信号，Agent 正在关闭...")
+			return
+		}
+	}
+}
+
+// maskToken 对令牌做脱敏处理，仅用于日志输出
+func maskToken(token string) string {
+	if token == "" {
+		return "(empty)"
+	}
+	if len(token) <= 4 {
+		return "****"
+	}
+	return token[:4] + "****"
+}