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/option/errs.go

@@ -0,0 +1,13 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package option
+
+const (
+	errInvalidParams       = "无效的参数"
+	errOptionInitFailed    = "系统选项初始化失败"
+	errGeoIPProvider       = "归属方式仅支持 disabled、mmdb、ip-api、geojs、ipinfo"
+	errGeoIPIPEmpty        = "IP 不能为空"
+	errGeoIPIPInvalid      = "IP 格式无效"
+	errGeoIPLookupDisabled = "GeoIP 查询已禁用"
+)