feat(vpn): add VPN server management and route-based VPN access control

ts_interfaces/data/remoteingress.ts

@@ -51,11 +51,21 @@ export interface IRouteRemoteIngress {
   edgeFilter?: string[];
 }
 
+/**
+ * Route-level VPN access configuration.
+ * When attached to a route, restricts access to VPN clients only.
+ */
+export interface IRouteVpn {
+  /** Whether this route requires VPN access */
+  required: boolean;
+}
+
 /**
  * Extended route config used within dcrouter.
- * Adds the optional `remoteIngress` property to SmartProxy's IRouteConfig.
+ * Adds optional `remoteIngress` and `vpn` properties to SmartProxy's IRouteConfig.
  * SmartProxy ignores unknown properties at runtime.
  */
 export type IDcRouterRouteConfig = IRouteConfig & {
   remoteIngress?: IRouteRemoteIngress;
+  vpn?: IRouteVpn;
 };