feat: Allow agent bots to update custom attributes in accessible conversations (#11447)

Previously, agent bots weren’t allowed to edit custom attributes in
conversations. But with AI, it’s now more feasible to return accurate
and useful attributes. Since there’s no strong reason to block this,
this PR enables bots to update custom attributes.

Fixes https://github.com/chatwoot/chatwoot/issues/11378

app/controllers/concerns/access_token_auth_helper.rb

@@ -1,6 +1,6 @@
 module AccessTokenAuthHelper
   BOT_ACCESSIBLE_ENDPOINTS = {
-    'api/v1/accounts/conversations' => %w[toggle_status toggle_priority create update],
+    'api/v1/accounts/conversations' => %w[toggle_status toggle_priority create update custom_attributes],
     'api/v1/accounts/conversations/messages' => ['create'],
     'api/v1/accounts/conversations/assignments' => ['create']
   }.freeze