fix: return promise from startSseServer

Author: punkpeye

README.md

@@ -59,7 +59,7 @@ import { startSseServer } from "mcp-proxy";
 
 const server = new Server();
 
-const { close } = startSseServer({
+const { close } = await startSseServer({
   port: 8080,
   endpoint: "/sse",
   server,

src/MCPProxy.ts

@@ -211,7 +211,7 @@ const startSending = async (transport: SSEServerTransport) => {
   }
 };
 
-export const startSseServer = ({
+export const startSseServer = async ({
   port,
   server,
   endpoint,