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.

internal/apps/openflare/pages/errs.go

@@ -0,0 +1,27 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package pages
+
+const (
+	errPagesProjectNotFound          = "Pages 项目不存在"
+	errPagesSlugExists               = "Pages 项目标识已存在"
+	errPagesNameRequired             = "Pages 项目名称不能为空"
+	errPagesSlugInvalid              = "Pages 项目标识只能包含小写字母、数字和连字符"
+	errPagesDeleteReferenced         = "Pages 项目已被规则引用，不能删除"
+	errPagesDeploymentNotFound       = "Pages 部署不存在"
+	errPagesDeploymentMismatch       = "Pages 部署不属于该项目"
+	errPagesDeleteActiveDeploy       = "不能删除当前激活的 Pages 部署"
+	errPagesPackageMissing           = "缺少 Pages 部署包"
+	errPagesPackageNotZip            = "Pages 部署包必须是 .zip 文件"
+	errPagesPackageInvalidZip        = "Pages 部署包不是有效 zip 文件"
+	errPagesPackageEmpty             = "Pages 部署包不能为空"
+	errPagesAPIProxyPathRequired     = "启用 API 反代时，匹配路径不能为空"
+	errPagesAPIProxyPathPrefix       = "API 反代匹配路径必须以 '/' 开头"
+	errPagesAPIProxyPassRequired     = "启用 API 反代时，后端服务地址不能为空"
+	errPagesAPIProxyPassInvalid      = "API 反代后端服务地址必须是有效的 HTTP/HTTPS URL"
+	errPagesPackagePathEmpty         = "Pages 部署包路径为空"
+	errPagesPackageUploadMissing     = "Pages 部署包上传记录不存在"
+	errPagesPackageNotInActiveConfig = "Pages 部署尚未进入激活配置"
+	errPagesInvalidSnapshotFormat    = "配置快照格式无效"
+)