feat(store): change default storage type to local filesystem

Add migration scripts for existing instances without a storage setting
to explicitly preserve DATABASE as their storage type, ensuring backward
compatibility. Change the default for new installations to LOCAL to
improve out-of-the-box performance.

store/instance_setting.go

@@ -169,7 +169,7 @@ func (s *Store) GetInstanceMemoRelatedSetting(ctx context.Context) (*storepb.Ins
 }
 
 const (
-	defaultInstanceStorageType       = storepb.InstanceStorageSetting_DATABASE
+	defaultInstanceStorageType       = storepb.InstanceStorageSetting_LOCAL
 	defaultInstanceUploadSizeLimitMb = 30
 	defaultInstanceFilepathTemplate  = "assets/{timestamp}_{filename}"
 )

store/migration/mysql/0.26/03__migrate_storage_setting.sql

+-- Set storage type to DATABASE for existing instances that have no storage setting configured.
+-- This preserves backward-compatible behavior before the default was changed to LOCAL.
+INSERT INTO system_setting (name, value, description)
+SELECT 'STORAGE', '{"storageType":"DATABASE"}', ''
+FROM DUAL
+WHERE NOT EXISTS (SELECT 1 FROM system_setting WHERE name = 'STORAGE');

store/migration/postgres/0.26/03__migrate_storage_setting.sql

+-- Set storage type to DATABASE for existing instances that have no storage setting configured.
+-- This preserves backward-compatible behavior before the default was changed to LOCAL.
+INSERT INTO system_setting (name, value, description)
+SELECT 'STORAGE', '{"storageType":"DATABASE"}', ''
+WHERE NOT EXISTS (SELECT 1 FROM system_setting WHERE name = 'STORAGE');

store/migration/sqlite/0.26/05__migrate_storage_setting.sql

+-- Set storage type to DATABASE for existing instances that have no storage setting configured.
+-- This preserves backward-compatible behavior before the default was changed to LOCAL.
+INSERT INTO system_setting (name, value, description)
+SELECT 'STORAGE', '{"storageType":"DATABASE"}', ''
+WHERE NOT EXISTS (SELECT 1 FROM system_setting WHERE name = 'STORAGE');

store/test/instance_setting_test.go

@@ -193,7 +193,7 @@ func TestInstanceSettingStorageSetting(t *testing.T) {
 	storageSetting, err := ts.GetInstanceStorageSetting(ctx)
 	require.NoError(t, err)
 	require.NotNil(t, storageSetting)
-	require.Equal(t, storepb.InstanceStorageSetting_DATABASE, storageSetting.StorageType)
+	require.Equal(t, storepb.InstanceStorageSetting_LOCAL, storageSetting.StorageType)
 	require.Equal(t, int64(30), storageSetting.UploadSizeLimitMb)
 	require.Equal(t, "assets/{timestamp}_{filename}", storageSetting.FilepathTemplate)