fix(migration): stop ownerId ping-pong on group DMs with 2 members

migrateFixOneOnOneOwnerIds was too aggressive — it set owner_id=NULL
on any 2-member channel, including group DMs that happened to have 2
members. The group DM repair then restored owner_id, creating noisy
logs every restart.

Now only targets channels with NULL or 32-char hex federatedId
(true 1-on-1 DMs), skipping UUID-format group DMs.

packages/server/src/db/migrate.ts

@@ -1993,6 +1993,7 @@ function migrateFixOneOnOneOwnerIds(db: Database.Database): void {
         HAVING COUNT(*) = 2
       )
       AND owner_id IS NOT NULL
+      AND (federated_id IS NULL OR length(federated_id) = 32)
     `).run();
 
     if (result.changes > 0) {