fix(rustproxy): Use cooperative cancellation for background tasks, prune stale caches and metric entries, and switch tests to dynamic port allocation to avoid port conflicts

test/test.metrics-new.ts

@@ -2,14 +2,16 @@ import { expect, tap } from '@git.zone/tstest/tapbundle';
 import * as plugins from '../ts/plugins.js';
 import { SmartProxy } from '../ts/index.js';
 import * as net from 'net';
+import { findFreePorts, assertPortsFree } from './helpers/port-allocator.js';
 
 let smartProxyInstance: SmartProxy;
 let echoServer: net.Server;
-const echoServerPort = 47300;
-const proxyPort = 47301;
+let echoServerPort: number;
+let proxyPort: number;
 
 // Create an echo server for testing
 tap.test('should create echo server for testing', async () => {
+  [echoServerPort, proxyPort] = await findFreePorts(2);
   echoServer = net.createServer((socket) => {
     socket.on('data', (data) => {
       socket.write(data); // Echo back the data
@@ -267,6 +269,8 @@ tap.test('should clean up resources', async () => {
       resolve();
     });
   });
+
+  await assertPortsFree([echoServerPort, proxyPort]);
 });
 
 export default tap.start();