Fix/auth listener leaks

[sudorishabh]

Fix: Cleanup auth listeners on component unmount to prevent memory leaks

fix: #1196

What does this PR do?

While reviewing the auth event listeners in our core React components, I noticed a potential silent memory leak and race condition.

In EmbeddedChat, ChatBody, and ChatInput, we were subscribing to RCInstance.auth.onAuthChange() inside useEffect, but we weren’t cleaning up those subscriptions when the components unmounted or re-rendered. This means that on every re-render, a new callback would get added to the authListeners array and stay there indefinitely.

In this PR I:

Refactored the anonymous inline callbacks into named functions.

Added proper cleanup in the useEffect hooks using return () => RCInstance.auth.removeAuthListener(handleAuthChange);

Before

useEffect(() => {
  RCInstance.auth.onAuthChange((user) => {
    if (user) {
      RCInstance.addMessageListener(addMessage);
      RCInstance.addMessageDeleteListener(removeMessage);
      RCInstance.addActionTriggeredListener(onActionTriggerResponse);
      RCInstance.addUiInteractionListener(onActionTriggerResponse);
    }
  });

  return () => {
    RCInstance.removeMessageListener(addMessage);
    RCInstance.removeMessageDeleteListener(removeMessage);
    RCInstance.removeActionTriggeredListener(onActionTriggerResponse);
    RCInstance.removeUiInteractionListener(onActionTriggerResponse);
  };
}, [RCInstance, addMessage, removeMessage, onActionTriggerResponse]);

After

  useEffect(() => {
    const handleAuthChange = (user) => {
      if (user) {
        RCInstance.addMessageListener(addMessage);
        RCInstance.addMessageDeleteListener(removeMessage);
        RCInstance.addActionTriggeredListener(onActionTriggerResponse);
        RCInstance.addUiInteractionListener(onActionTriggerResponse);
      }
    };

    RCInstance.auth.onAuthChange(handleAuthChange);

    return () => {
      RCInstance.auth.removeAuthListener(handleAuthChange);
      RCInstance.removeMessageListener(addMessage);
      RCInstance.removeMessageDeleteListener(removeMessage);
      RCInstance.removeActionTriggeredListener(onActionTriggerResponse);
      RCInstance.removeUiInteractionListener(onActionTriggerResponse);
    };
  }, [RCInstance, addMessage, removeMessage, onActionTriggerResponse]);

Files with the issue - EmbeddedChat.js, ChatInput.js, ChatBody.js

Note: The PR will be ready for live testing at https://rocketchat.github.io/EmbeddedChat/pulls/pr-1196 after approval.