Remove message.owner_user_id field and implement db migrations

scnserver/db/context.go

@@ -0,0 +1,15 @@
+package db
+
+import (
+	"gogs.mikescher.com/BlackForestBytes/goext/sq"
+	"time"
+)
+
+type TxContext interface {
+	Deadline() (deadline time.Time, ok bool)
+	Done() <-chan struct{}
+	Err() error
+	Value(key any) any
+
+	GetOrCreateTransaction(db DatabaseImpl) (sq.Tx, error)
+}