* MM-68160: Show post reminder ack in RHS for reply reminders
Set the reminder confirmation ephemeral post root_id to the thread root
when the reminder is set on a reply, matching how thread views key posts.
Re-enable websocket integration tests for reminders and add coverage for
reply vs root behavior.
Made-with: Cursor
* SetPostReminder: validate post before persisting reminder
Read the post and reminder metadata before inserting into PostReminders so
a failed GetSinglePost or metadata lookup cannot leave an orphaned row.
Made-with: Cursor