feat: add PostgreSQL migration runner

server/migrations/runner_test.go

@@ -0,0 +1,15 @@
+package migrations
+
+import (
+	"context"
+	"testing"
+)
+
+func TestApplyRejectsMissingDatabaseOrDirectory(t *testing.T) {
+	if err := Apply(context.Background(), nil, "."); err == nil {
+		t.Fatal("nil database accepted")
+	}
+	if err := Apply(context.Background(), nil, ""); err == nil {
+		t.Fatal("empty directory accepted")
+	}
+}