Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: mathieucarbou

src/AsyncEventSource.cpp

@@ -200,7 +200,7 @@ AsyncEventSourceClient::~AsyncEventSourceClient() {
 
 bool AsyncEventSourceClient::_queueMessage(const char *message, size_t len) {
 #ifdef ESP32
-  // length() is not thread-safe, thus acquiring the lock before this call..
+  // Protect message queue access (size checks and modifications) which is not thread-safe.
   std::lock_guard<std::recursive_mutex> lock(_lockmq);
 #endif