feat(nodes): traffic-writer queue, full-mirror sync, WS event fixes

- Traffic-writer single-consumer queue (web/service/traffic_writer.go)
  serialises every DB write that touches up/down/all_time/last_online
  (AddTraffic, SetRemoteTraffic, Reset*, UpdateClientTrafficByEmail) so
  overlapping goroutines can no longer clobber each other's column-scoped
  Updates with a stale tx.Save.

- DB pool: WAL + busy_timeout=10s + synchronous=NORMAL + _txlock=
  immediate, MaxOpenConns=8 / MaxIdleConns=4. The immediate-tx PRAGMA
  fixes residual "database is locked [0ms]" cases where deferred-tx
  writer-upgrade conflicts bypass busy_timeout.

- SetRemoteTraffic full-mirrors node-authoritative state into central:
  settings JSON, remark, listen, port, total, expiry, all_time, enable,
  plus per-client total/expiry/reset/all_time. Inbounds and
  client_traffics rows present on node but missing from central are
  created; rows missing from snap are deleted (with cascading
  client_traffics removal).

- NodeTrafficSyncJob detects structural changes from the mirror and
  broadcasts invalidate(inbounds) so open central UIs re-fetch via REST
  on node-side add/del/edit without manual refresh.

- XrayTrafficJob broadcasts invalidate(inbounds) when auto-disable flips
  client_traffics.enable so the per-client toggle reflects depletion
  without manual refresh.

- Frontend: inbounds page now subscribes to the BroadcastInbounds 'inbounds'
  WS event (full-list pushes from add/del/update controllers were silently
  dropped). Fixes invalidate payload field (dataType -> type). Restart-
  panel modal switched from Promise-wrap to onOk-only so Cancel actually
  cancels.

- Node files trimmed of stale prose-comments; cron cadence dropped
  10s -> 5s to match the inbounds page UX.

- README badges and Go module path bumped v2 -> v3 to match module rename.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/job/node_heartbeat_job.go

@@ -11,37 +11,22 @@ import (
 	"github.com/mhsanaei/3x-ui/v3/web/websocket"
 )
 
-// nodeHeartbeatConcurrency caps how many remote panels we probe at once.
-// Plenty of headroom for typical deployments (tens of nodes) without
-// letting a misconfigured run open thousands of sockets at once.
-const nodeHeartbeatConcurrency = 32
+const (
+	nodeHeartbeatConcurrency    = 32
+	nodeHeartbeatRequestTimeout = 4 * time.Second
+)
 
-// nodeHeartbeatRequestTimeout bounds a single probe. The cron is @every 10s,
-// so this needs to stay well under that to avoid run pile-up.
-const nodeHeartbeatRequestTimeout = 6 * time.Second
-
-// NodeHeartbeatJob probes every enabled remote node once per cron tick
-// and persists the result. Disabled nodes are skipped entirely so a
-// long-broken node can be parked without burning sockets every 10s.
 type NodeHeartbeatJob struct {
 	nodeService service.NodeService
-
-	// Coarse mutex prevents two ticks running concurrently if probes
-	// pile up under network failure. The next tick simply skips when
-	// the previous one is still draining.
-	running sync.Mutex
+	running     sync.Mutex
 }
 
-// NewNodeHeartbeatJob constructs a heartbeat job. The robfig/cron
-// scheduler will hand the same instance to every tick, so the
-// running mutex carries across runs as intended.
 func NewNodeHeartbeatJob() *NodeHeartbeatJob {
 	return &NodeHeartbeatJob{}
 }
 
 func (j *NodeHeartbeatJob) Run() {
 	if !j.running.TryLock() {
-		// Previous tick still in flight — skip this one.
 		return
 	}
 	defer j.running.Unlock()
@@ -71,10 +56,6 @@ func (j *NodeHeartbeatJob) Run() {
 	}
 	wg.Wait()
 
-	// Push the fresh list to any open Nodes page over WebSocket so the
-	// status / latency / cpu / mem cells update without the user clicking
-	// refresh. Skip the DB read entirely when no browser is connected —
-	// matches the gating pattern in xray_traffic_job.
 	if !websocket.HasClients() {
 		return
 	}
@@ -86,10 +67,6 @@ func (j *NodeHeartbeatJob) Run() {
 	websocket.BroadcastNodes(updated)
 }
 
-// probeOne runs a single probe and persists the result. We deliberately
-// don't return errors — partial failures across the node set should not
-// abort other probes, and the LastError column carries the message for
-// the UI to surface.
 func (j *NodeHeartbeatJob) probeOne(n *model.Node) {
 	ctx, cancel := context.WithTimeout(context.Background(), nodeHeartbeatRequestTimeout)
 	defer cancel()
@@ -100,8 +77,6 @@ func (j *NodeHeartbeatJob) probeOne(n *model.Node) {
 		patch.Status = "online"
 	}
 	if updErr := j.nodeService.UpdateHeartbeat(n.Id, patch); updErr != nil {
-		// A row deleted mid-tick produces "rows affected = 0", which
-		// gorm reports as nil — so any error we get here is real.
 		logger.Warning("node heartbeat: update node", n.Id, "failed:", updErr)
 	}
 }