Free module list nodes during shutdown

- free the GList container allocated via add_module() during exit_modules()
- reset module_head to NULL after g_list_free() to avoid stale pointer reuse
- keep module->exit callbacks unchanged while eliminating module list node leak

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: MyungJoo Ham <myungjoo.ham@samsung.com>

Author: cursoragent

daemon/modules.c

@@ -78,4 +78,7 @@ exit_modules (void *data)
     if (module->exit)
       module->exit (data);
   }
+
+  g_list_free (module_head);
+  module_head = NULL;
 }