Enhance socket cleanup and management for improved connection handling

- Refactor cleanupSocket function to support options for immediate destruction, allowing drain, and grace periods.
- Introduce createIndependentSocketHandlers for better management of half-open connections between client and server sockets.
- Update various handlers (HTTP, HTTPS passthrough, HTTPS terminate) to utilize new cleanup and socket management functions.
- Implement custom timeout handling in socket setup to prevent immediate closure during keep-alive connections.
- Add tests for long-lived connections and half-open connection scenarios to ensure stability and reliability.
- Adjust connection manager to handle socket cleanup based on activity status, improving resource management.

ts/proxies/http-proxy/connection-pool.ts

@@ -134,7 +134,7 @@ export class ConnectionPool {
         if ((connection.isIdle && now - connection.lastUsed > idleTimeout) ||
             connections.length > (this.options.connectionPoolSize || 50)) {
           
-          cleanupSocket(connection.socket, `pool-${host}-idle`);
+          cleanupSocket(connection.socket, `pool-${host}-idle`, { immediate: true }).catch(() => {});
           
           connections.shift(); // Remove from pool
           removed++;
@@ -164,7 +164,7 @@ export class ConnectionPool {
       this.logger.debug(`Closing ${connections.length} connections to ${host}`);
       
       for (const connection of connections) {
-        cleanupSocket(connection.socket, `pool-${host}-close`);
+        cleanupSocket(connection.socket, `pool-${host}-close`, { immediate: true }).catch(() => {});
       }
     }