fix: etcp_connect_timeout_tb=0 in utun_instance_create (missing init)

utun_instance_create() allocated with u_calloc (zeroed) but never
set etcp_connect_timeout_tb. utun_instance_create_from_config() had it
at line 371, but utun_instance_create (used by chatgui) was missing.
Timer with tb=0 fires instantly → CLOSE sent before handshake completes.
Diagnostics confirmed: value_tb=0, tb=0, delta_tb=0 on Windows chatgui.

src/utun_instance.c

@@ -317,7 +317,8 @@ struct UTUN_INSTANCE* utun_instance_create(struct UASYNC* ua, const char *config
         free_config(config);
         return NULL;
     }
-    
+    instance->etcp_connect_timeout_tb = 20000;
+
     // Init stats_dir from config file path
     {
         const char* last_sep = NULL;