feat(server): add optional PROXY protocol v2 headers for socket-based userspace NAT forwarding

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartvpn',
-  version: '1.11.0',
+  version: '1.12.0',
   description: 'A VPN solution with TypeScript control plane and Rust data plane daemon'
 }

ts/smartvpn.interfaces.ts

@@ -118,6 +118,11 @@ export interface IVpnServerConfig {
   /** Server-level IP block list — applied at TCP accept, before Noise handshake.
    *  Supports exact IPs, CIDR, wildcards, ranges. */
   connectionIpBlockList?: string[];
+  /** When true and forwardingMode is 'socket', the userspace NAT engine prepends
+   *  PROXY protocol v2 headers on outbound TCP connections, conveying the VPN client's
+   *  tunnel IP as the source address. This allows downstream services (e.g. SmartProxy)
+   *  to see the real VPN client identity instead of 127.0.0.1. */
+  socketForwardProxyProtocol?: boolean;
 }
 
 export interface IVpnServerOptions {