P7: restore agent node type, agent heartbeat expiry, build-version injection, remove log/history/xray-metrics modules, optional sub port

- nodes: port node-type (traditional/agent) picker back from web-src into
  the embedded frontend; backend annotates NodeView.nodeType from
  agent_nodes bindings; fix agent-node update path (skip reachability
  probe and apiToken requirement for agent-managed nodes); restore i18n
  keys in all 13 locales; install command now uses the Gitea mirror
- jobs: expire agent-bound nodes whose agent_nodes.last_seen is older
  than max(3x heartbeat interval, 120s) = 180s; last_seen=0 (never
  registered) is left untouched; transitions reuse UpdateHeartbeat +
  node event broadcast
- config: GetBaseVersion honors ldflags-injected buildVersion; release
  builds inject 3.7.0-agent.1 so the panel no longer reports a phantom
  update against the Gitea release tag
- logger/server: remove the three log viewers (panel/xray/amneziawg),
  their API endpoints and the 10240-entry in-memory log buffer; file
  logging via lumberjack unchanged; tests assert via a new optional
  logger hook instead of the removed buffer
- server: remove system history and xray metrics modules end to end
  (endpoints, sampling appends in RefreshStatus, per-minute persist
  cron, gob snapshot/restore, XrayMetricsService); realtime status and
  per-node history are untouched
- settings: subPort may be 0/unset - subscription links are generated
  without a port while the subscription service keeps binding the
  default 2096; the settings form declares the cleared state via
  onNumber's new onClear option instead of snapping back to 1

internal/web/service/node.go

@@ -363,7 +363,9 @@ func (s *NodeService) GetViewById(id int) (*NodeView, error) {
 	if err != nil {
 		return nil, err
 	}
-	return toNodeView(n), nil
+	view := toNodeView(n)
+	annotateNodeTypes([]*NodeView{view})
+	return view, nil
 }
 
 // NodeExists reports whether a node with the given id exists on this panel.
@@ -566,7 +568,10 @@ func (s *NodeService) UpdateFromRequest(id int, req *NodeMutationRequest) error
 			return err
 		}
 	}
-	if apiToken == "" && in.Enable && in.TlsVerifyMode != "mtls" {
+	// Agent nodes authenticate with their agent token, never a panel API
+	// token — the requirement below must not make them uneditable.
+	isAgent := req.NodeType == "agent" || s.IsAgentManaged(id)
+	if !isAgent && apiToken == "" && in.Enable && in.TlsVerifyMode != "mtls" {
 		return common.NewError("apiToken is required unless mtls is enabled")
 	}
 	updates := map[string]any{