remove feed block after CLOSE: feed must remain active for streaming and half_close after FIN

src/tcp_proxy.c

@@ -188,7 +188,7 @@ static void transport_to_uip_cb(struct ll_queue* q, void* arg) {
 // Helper: feed data from transport_to_uip queue to lwIP TCP
 // ====================================================================
 static void proxy_feed_from_transport(struct proxy_conn *pc) {
-    if (!pc->transport_to_uip || !pc->pcb || pc->closing_sent) return;
+    if (!pc->transport_to_uip || !pc->pcb) return;
     int sent_any = 0;
     int entries_fed = 0;
     while (1) {