feat(telemetry): agent 心跳遥测上报+节点列表覆写(第13条)

agent 每 60s 心跳捎带遥测: agentVersion/xrayVersion(按 mtime 缓存重读)/
uptime/最近一次主控请求 RTT/cpu%/mem%/公网 v4+v6(公网优先, ULA/私网兜底);
主控心跳处理按指针语义只存上报字段, 旧 agent 无遥测行为不变;
agent_nodes 加法迁移存遥测, 节点列表对 agent 行覆写真值,
panelVersion 显示 "agent <版本>", NodeView 新增 ipv4/ipv6。

internal/agent/agent.go

@@ -14,6 +14,8 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/mhsanaei/3x-ui/v3/internal/config"
@@ -64,6 +66,15 @@ type Agent struct {
 	xrayAPI        xray.XrayAPI
 	apiPort        int
 	baselineLoaded bool
+
+	// Heartbeat telemetry state (P13): last measured master-request RTT
+	// and the mtime-keyed xray version cache.
+	lastRTTms  atomic.Int64
+	hasRTT     atomic.Bool
+	xrayVerMu  sync.Mutex
+	xrayVer    string
+	xrayVerFor string // binary path the cached version was read from
+	xrayVerMod time.Time
 }
 
 // New creates a new agent instance
@@ -110,7 +121,7 @@ func (a *Agent) Register() error {
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Authorization", "Bearer "+a.config.Token)
 
-	resp, err := a.httpClient.Do(req)
+	resp, err := a.do(req)
 	if err != nil {
 		return fmt.Errorf("register failed: %w", err)
 	}
@@ -241,12 +252,25 @@ func (a *Agent) Stop() {
 	close(a.stopCh)
 }
 
+// do performs one master request and records its round-trip time as the
+// node->master latency sample reported by the next heartbeat (P13).
+func (a *Agent) do(req *http.Request) (*http.Response, error) {
+	start := time.Now()
+	resp, err := a.httpClient.Do(req)
+	if err == nil {
+		a.lastRTTms.Store(time.Since(start).Milliseconds())
+		a.hasRTT.Store(true)
+	}
+	return resp, err
+}
+
 // sendHeartbeat sends a heartbeat to the master
 func (a *Agent) sendHeartbeat() error {
 	url := fmt.Sprintf("%s/panel/api/agent/heartbeat", a.config.MasterURL)
 	payload := map[string]interface{}{
 		"token":     a.config.Token,
 		"timestamp": time.Now().Unix(),
+		"telemetry": a.collectTelemetry(),
 	}
 	body, _ := json.Marshal(payload)
 	req, err := http.NewRequest("POST", url, bytes.NewReader(body))
@@ -256,7 +280,7 @@ func (a *Agent) sendHeartbeat() error {
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Authorization", "Bearer "+a.config.Token)
 
-	resp, err := a.httpClient.Do(req)
+	resp, err := a.do(req)
 	if err != nil {
 		return err
 	}
@@ -276,7 +300,7 @@ func (a *Agent) fetchAndApplyConfig() error {
 	}
 	req.Header.Set("Authorization", "Bearer "+a.config.Token)
 
-	resp, err := a.httpClient.Do(req)
+	resp, err := a.do(req)
 	if err != nil {
 		return err
 	}
@@ -509,7 +533,7 @@ func (a *Agent) postTrafficReport(report trafficReport) error {
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Authorization", "Bearer "+a.config.Token)
 
-	resp, err := a.httpClient.Do(req)
+	resp, err := a.do(req)
 	if err != nil {
 		return err
 	}