Fix segmentation fault by not freeing shared SSL in remove_tunnel

- Prevent SSL double-free when individual tunnels are closed
- SSL contexts are managed only at connection level
- Fixes crashes when server closes tunnels

wssshtools/tunnel.c

@@ -133,9 +133,8 @@ void remove_tunnel(const char *request_id) {
             if (active_tunnels[i]->sock >= 0) {
                 close(active_tunnels[i]->sock);
             }
-            if (active_tunnels[i]->ssl) {
-                SSL_free(active_tunnels[i]->ssl);
-            }
+            // Don't free SSL here - it's managed at the connection level
+            active_tunnels[i]->ssl = NULL;
             if (active_tunnels[i]->outgoing_buffer) {
                 frame_buffer_free(active_tunnels[i]->outgoing_buffer);
             }