refactor(repo): replace legacy openflare-server with Wavelet rename

Delete the old monolithic openflare-server implementation and rename
Wavelet/ to openflare-server/ to complete the migration consolidation.
Update CI workflows, agent Dockerfiles, and deployment docs for the new
layout (frontend/, docker/Dockerfile).

openflare-server/internal/testhelper/cleanup.go

@@ -0,0 +1,17 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package testhelper
+
+// RegisterCleanup registers an extra cleanup hook invoked by SetupTestEnvironment.
+func RegisterCleanup(fn func()) {
+	extraCleanups = append(extraCleanups, fn)
+}
+
+var extraCleanups []func()
+
+func runExtraCleanups() {
+	for _, fn := range extraCleanups {
+		fn()
+	}
+}