fix: add process-alive check after starting looper in audio routing tests

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

test_audio_routing.c

@@ -181,6 +181,13 @@ static int start_looper(const char *client_name) {
     
     // Wait for looper to start
     usleep(500000);  // 500ms
+    
+    // Check if looper is still running
+    if (kill(looper_pid, 0) != 0) {
+        fprintf(stderr, "Looper process died\n");
+        return -1;
+    }
+    
     return 0;
 }