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.
b5ebc47637