Removes touch: true from the belongs_to :conversation association on
Message and consolidates the conversation timestamp update into the
existing set_conversation_activity callback.
Previously, every message save triggered two separate UPDATE queries on
the conversation — one from Rails' touch (updating updated_at) and
another from set_conversation_activity (updating last_activity_at). This
combines both into a single update_columns call, reducing write load on
the conversations table on every message creation.
### What changed
- Removed touch: true from belongs_to :conversation in Message
- Added updated_at: created_at to the existing update_columns call in
set_conversation_activity
c6f82783ba