refactor(backend): rename OpenFlare directory to lowercase openflare

backend/openflare/plugins/server/domain/fleet/relay/errs.go

@@ -0,0 +1,11 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+// Package relay provides relay node management and authentication for the OpenFlare platform.
+package relay
+
+const (
+	//nolint:gosec // error message text, not a credential
+	errAgentTokenInvalid     = "无权进行此操作，Agent Token 无效"
+	errRelayNodeTypeMismatch = "此节点不是 TunnelRelay 类型"
+)