fix(node): keep client/inbound edits working when a node is offline (#4923, #4931)

Node-backed client and inbound edits no longer hard-fail when the backing node is offline or disabled. Edits commit to the panel DB immediately and reconcile to the node when it reconnects (eventual consistency); the panel is the single source of truth for desired config.

- Add Node.ConfigDirty/ConfigDirtyAt; mark a node dirty when an edit commits without reaching it (cleared via CAS on ConfigDirtyAt after a full reconcile).
- nodePushPlan() reads node state fresh from the DB, skips the push for offline/disabled nodes (no 10s hang), and treats push failures as non-fatal across every mutation path (client add/update/del + bulk + attach/detach; inbound add/update/del/toggle/resetTraffic).
- ReconcileNode() pushes the panel's desired config to a node on reconnect (refreshing the remote tag cache first) and prunes node-side orphans; runs before the traffic pull in the node sync job.
- While a node is dirty the traffic pull applies only up/down deltas and node-initiated disables, never overwriting desired config from a stale node snapshot.
- Surface a non-blocking 'saved; will sync on reconnect' warning to the UI.

Validated with a two-panel Docker E2E: client delete/update, attach/detach, and inbound add/delete all reconcile correctly offline -> reconnect.

web/service/node_client_traffic_sum_test.go

@@ -36,7 +36,7 @@ func syncNode(t *testing.T, svc *InboundService, nodeID int, tag string, stats .
 	snap := &runtime.TrafficSnapshot{
 		Inbounds: []*model.Inbound{{Tag: tag, ClientStats: stats}},
 	}
-	if _, err := svc.setRemoteTrafficLocked(nodeID, snap); err != nil {
+	if _, err := svc.setRemoteTrafficLocked(nodeID, snap, false); err != nil {
 		t.Fatalf("setRemoteTrafficLocked node %d: %v", nodeID, err)
 	}
 }