feat: add verbose logging and log-level selection (#1941)

examples/server/runtime.h

@@ -22,7 +22,7 @@ struct SDSvrParams {
     int listen_port       = 1234;
     std::string serve_html_path;
     bool normal_exit = false;
-    bool verbose     = false;
+    sd_log_level_t log_level = SD_LOG_INFO;
     bool color       = false;
 
     ArgOptions get_options();