chore: Enable Participating tab for conversations (#11714)

## Summary

This PR enables the **Participating** conversation view in the main
sidebar and keeps the behavior aligned with existing conversation views.

## What changed

- Added **Participating** under Conversations in the new sidebar.
- Added a guard in conversation realtime `addConversation` flow so
generic `conversation.created` events are not injected while the user is
on Participating view.
- Added participating route mapping in conversation-list redirect helper
so list redirects resolve correctly to `/participating/conversations`.

## Scope notes

- Kept changes minimal and consistent with current `develop` behavior.
- No additional update-event filtering was added beyond what existing
views already do.

---------


Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>

app/javascript/dashboard/helper/URLHelper.js

@@ -51,6 +51,7 @@ export const conversationListPageURL = ({
   } else if (conversationType) {
     const urlMap = {
       mention: 'mentions/conversations',
+      participating: 'participating/conversations',
       unattended: 'unattended/conversations',
     };
     url = `accounts/${accountId}/${urlMap[conversationType]}`;