refactor(repo): consolidate openflare-server to root and move subprojects to internal/apps

- Merge all files inside openflare-server to the repository root directory.
- Relocate agent, relay, and flared subprojects from internal/ to internal/apps/.
- Combine docker-compose files and update build context paths to root.
- Update GitHub workflows and Dockerfiles to refer to new directories and package names.
- Rewrite Go package imports across all files.
- Resolve database renew test race condition and clean up docs.

pkg/httppool/httppool_test.go

@@ -0,0 +1,37 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package httppool
+
+import (
+	"testing"
+	"time"
+)
+
+func TestDefaultTransport(t *testing.T) {
+	tr1 := DefaultTransport()
+	if tr1 == nil {
+		t.Fatal("DefaultTransport() returned nil")
+	}
+
+	tr2 := DefaultTransport()
+	if tr1 != tr2 {
+		t.Error("DefaultTransport() did not return a singleton instance")
+	}
+}
+
+func TestNewClient(t *testing.T) {
+	timeout := 15 * time.Second
+	client := NewClient(timeout)
+	if client == nil {
+		t.Fatal("NewClient() returned nil")
+	}
+
+	if client.Timeout != timeout {
+		t.Errorf("NewClient() timeout = %v, want %v", client.Timeout, timeout)
+	}
+
+	if client.Transport != DefaultTransport() {
+		t.Error("NewClient() is not configured with the default transport")
+	}
+}