feat: switch monitor client to Docker-first runtime

- remove install.sh-based deployment path
- add multi-stage Dockerfile for HarborForge.Monitor
- support HF_MONITER_* env vars and keep HF_MONITOR_* compatibility
- add rootfs-aware host metric collection for Docker deployment

internal/telemetry/telemetry.go

@@ -55,7 +55,11 @@ func BuildPayload(ctx context.Context, cfg config.Config) (Payload, error) {
 		payload.MemPct = round1(vm.UsedPercent)
 	}
 
-	diskUsage, err := disk.UsageWithContext(ctx, "/")
+	diskPath := cfg.RootFS
+	if diskPath == "" {
+		diskPath = "/"
+	}
+	diskUsage, err := disk.UsageWithContext(ctx, diskPath)
 	if err == nil {
 		payload.DiskPct = round1(diskUsage.UsedPercent)
 	}
@@ -75,7 +79,7 @@ func BuildPayload(ctx context.Context, cfg config.Config) (Payload, error) {
 		payload.UptimeSeconds = hostInfo.Uptime
 	}
 
-	nginxInstalled, nginxSites, err := detectNginx()
+	nginxInstalled, nginxSites, err := detectNginx(cfg.RootFS)
 	if err == nil {
 		payload.NginxInstalled = nginxInstalled
 		payload.NginxSites = nginxSites
@@ -109,12 +113,20 @@ func Send(ctx context.Context, client *http.Client, cfg config.Config, payload P
 	return nil
 }
 
-func detectNginx() (bool, []string, error) {
+func detectNginx(rootFS string) (bool, []string, error) {
 	installed := false
-	if _, err := exec.LookPath("nginx"); err == nil {
-		installed = true
+	if rootFS == "" {
+		if _, err := exec.LookPath("nginx"); err == nil {
+			installed = true
+		}
 	}
-	for _, path := range []string{"/etc/nginx/nginx.conf", "/usr/local/etc/nginx/nginx.conf", "/opt/homebrew/etc/nginx/nginx.conf"} {
+	for _, path := range []string{
+		rootPath(rootFS, "/etc/nginx/nginx.conf"),
+		rootPath(rootFS, "/usr/local/etc/nginx/nginx.conf"),
+		rootPath(rootFS, "/opt/homebrew/etc/nginx/nginx.conf"),
+		rootPath(rootFS, "/usr/sbin/nginx"),
+		rootPath(rootFS, "/usr/bin/nginx"),
+	} {
 		if _, err := os.Stat(path); err == nil {
 			installed = true
 			break
@@ -124,7 +136,7 @@ func detectNginx() (bool, []string, error) {
 		return false, []string{}, nil
 	}
 
-	dir := "/etc/nginx/sites-enabled"
+	dir := rootPath(rootFS, "/etc/nginx/sites-enabled")
 	entries, err := os.ReadDir(dir)
 	if err != nil {
 		if os.IsNotExist(err) {
@@ -155,3 +167,10 @@ func round1(v float64) float64 {
 func round2(v float64) float64 {
 	return float64(int(v*100+0.5)) / 100
 }
+
+func rootPath(rootFS, path string) string {
+	if rootFS == "" || rootFS == "/" {
+		return path
+	}
+	return filepath.Join(rootFS, strings.TrimPrefix(path, "/"))
+}