fix: Send CSAT survey only when agent can reply in conversation (#11584)

Fixes https://github.com/chatwoot/chatwoot/issues/11569

 ## Problem
On platforms like WhatsApp and Facebook Messenger, customers cannot
reply to messages after 24 hours (or other channel-specific messaging
windows). Despite this limitation, the system continued sending CSAT
surveys to customers outside their messaging window, making it
impossible for them to respond.

  ## Solution
Added a check for `conversation.can_reply?` in the
`should_send_csat_survey?` method. This leverages the existing
`MessageWindowService` which already handles all channel-specific
messaging window logic.

spec/models/conversation_spec.rb

@@ -435,6 +435,20 @@ RSpec.describe Conversation do
     end
   end
 
+  describe '#create_csat_not_sent_activity_message' do
+    subject(:create_csat_not_sent_activity_message) { conversation.create_csat_not_sent_activity_message }
+
+    let(:conversation) { create(:conversation) }
+
+    it 'creates CSAT not sent activity message' do
+      create_csat_not_sent_activity_message
+      expect(Conversations::ActivityMessageJob)
+        .to(have_been_enqueued.at_least(:once).with(conversation, { account_id: conversation.account_id, inbox_id: conversation.inbox_id,
+                                                                    message_type: :activity,
+                                                                    content: 'CSAT survey not sent due to outgoing message restrictions' }))
+    end
+  end
+
   describe 'unread_messages' do
     subject(:unread_messages) { conversation.unread_messages }