feat(webhooks): Emit inbox_updated when an inbox is disconnected (#14504)

Chatwoot now lets external apps know when an inbox loses its connection
and needs re-authentication. When a channel's authorization expires (for
example, an email inbox disconnects), Chatwoot fires an `inbox_updated`
webhook reflecting the new `reauthorization_required` status, and fires
it again once the inbox is re-authenticated. Integrators can keep their
own view of which inboxes are healthy without polling the API.

This is gated behind the `ENABLE_INBOX_EVENTS` installation flag — the
**Inbox updated** webhook subscription only appears in the dashboard
when that flag is enabled, so no event is offered that the backend
wouldn't dispatch.

Fixes
https://linear.app/chatwoot/issue/CW-7148/emit-inbox-webhook-when-an-inbox-is-disconnected

## How to test

1. Set `ENABLE_INBOX_EVENTS=true` and restart the app.
2. In **Settings → Integrations → Webhooks**, add a webhook and
subscribe to **Inbox updated**.
3. Disconnect an inbox — let an email/Instagram channel hit its
auth-error threshold, or run `inbox.channel.prompt_reauthorization!` in
a console.
4. The endpoint receives an `inbox_updated` event whose
`changed_attributes` shows `reauthorization_required` flipping to
`true`.
5. Re-authenticate the inbox (or run `inbox.channel.reauthorized!`) —
the endpoint receives the `true → false` transition.
6. Confirm the **Inbox updated** option is hidden when
`ENABLE_INBOX_EVENTS` is unset.

---------

Co-authored-by: Muhsin <12408980+muhsin-k@users.noreply.github.com>

app/javascript/dashboard/composables/useConfig.js

@@ -36,11 +36,18 @@ export function useConfig() {
    */
   const enterprisePlanName = config.enterprisePlanName;
 
+  /**
+   * Indicates whether inbox webhook events (ENABLE_INBOX_EVENTS) are enabled.
+   * @type {boolean}
+   */
+  const inboxEventsEnabled = config.inboxEventsEnabled === 'true';
+
   return {
     hostURL,
     vapidPublicKey,
     enabledLanguages,
     isEnterprise,
     enterprisePlanName,
+    inboxEventsEnabled,
   };
 }