feat(vpn transport): add QUIC transport support with auto fallback to WebSocket

ts/smartvpn.interfaces.ts

@@ -32,6 +32,10 @@ export interface IVpnClientConfig {
   mtu?: number;
   /** Keepalive interval in seconds (default: 30) */
   keepaliveIntervalSecs?: number;
+  /** Transport protocol: 'auto' (default, tries QUIC then WS), 'websocket', or 'quic' */
+  transport?: 'auto' | 'websocket' | 'quic';
+  /** For QUIC: SHA-256 hash of server certificate (base64) for cert pinning */
+  serverCertHash?: string;
 }
 
 export interface IVpnClientOptions {
@@ -68,6 +72,12 @@ export interface IVpnServerConfig {
   defaultRateLimitBytesPerSec?: number;
   /** Default burst size for new clients (bytes). Omit for unlimited. */
   defaultBurstBytes?: number;
+  /** Transport mode: 'both' (default, WS+QUIC), 'websocket', or 'quic' */
+  transportMode?: 'websocket' | 'quic' | 'both';
+  /** QUIC listen address (host:port). Defaults to listenAddr. */
+  quicListenAddr?: string;
+  /** QUIC idle timeout in seconds (default: 30) */
+  quicIdleTimeoutSecs?: number;
 }
 
 export interface IVpnServerOptions {