The GetChats SQL query ordered by (updated_at, id) DESC with no
pin_order awareness. A pinned chat with an old updated_at could
land on page 2+ and be invisible in the sidebar's Pinned section.
Add a 4-column ORDER BY: pinned-first flag DESC, negated pin_order
DESC, updated_at DESC, id DESC. The negation trick keeps all sort
columns DESC so the cursor tuple < comparison still works. Update
the after_id cursor clause to match the expanded sort key.
Fix the false handler comment claiming PinChatByID bumps updated_at.
Mathias Fredriksson
a62ead8588