docs(i18n): 恢复并补齐英文版 vitepress，README 默认改为英文

- README 默认英文：README.en.md → README.md（英文为默认），中文移至 README.zh-CN.md，语言切换链接同步
- 恢复被删除的 docs/en/ 英文文档（git 历史 cc5e53c5^），删除 4 篇已废弃文件
- 英文导航 config.ts 对齐中文结构（新增 Deployment/Changelog 侧栏，同步 Guide/Design 条目）
- 翻译 15 篇中文新增文档：guide 5 篇（certificates/pages-usage/proxy-config/uptime-kuma/zone-domain-migration）+ design 10 篇（zone-design/cloudflare-pointing/waf-orchestration/origin-error-page/edge-cache-design/pages-design/logstore/kuma-design/login-captcha/observability 三篇）
- en 首页更新（新增 Pages 特性、tagline 同步）；changelog 英文入口指向中文版
- vitepress 构建验证：43 个英文页面全部渲染

注意：29 篇旧英文文档为恢复版，部分内容（如 deployment/server、reference/configuration）可能落后于中文，需后续逐篇同步

docs/en/guide/index.md

@@ -0,0 +1,43 @@
+# Guide Overview
+
+You will learn: How the OpenFlare documentation is organized, which pages to read when running it for the first time, and where to start for deployment, usage, troubleshooting, and development.
+
+OpenFlare is a self-hosted OpenResty control plane. It integrates reverse proxy website configurations, configuration version publishing, Agent node synchronization, TLS certificates, and basic observability into a single management console, making it ideal for a single team or organization managing multiple proxy nodes.
+
+## Recommended Reading Path
+
+If you are new to OpenFlare, read the documents in the following order:
+
+1. [Quick Start](./quick-start.md): Start the Server using Docker Compose, log into the management console, and connect your first Agent.
+2. [Basic Usage](./usage.md): Learn common operations for website configs, origins, certificates, publishing, rollbacks, and observability.
+3. [Tunnel & Intranet Penetration](./tunnel-usage.md): Learn to deploy Relay and Client to achieve secure, public IP-free reverse penetration.
+4. [WAF Security Protection](./waf-usage.md): Master IP whitelisting/blacklisting, WAF auto IP group aggregation Expr rules, geographical restrictions, and PoW CC protection.
+5. [WAF Auto IP Group Expressions](./waf-ip-group-expr.md): Write auto IP group Expr rules and learn keyword definitions and presets.
+6. [Deployment Guide](../deployment/deployment.md): Deploy Server and Agent in closer-to-production environments.
+7. [Configurations Reference](../reference/configuration.md): Check Server environment variables, runtime Options, and Agent configurations.
+8. [Troubleshooting](./troubleshooting.md): Troubleshoot login, database, node sync, OpenResty application, and frontend build issues.
+
+## Role-Based Entrypoints
+
+| What do you want to do? | Recommended Entrance |
+| --- | --- |
+| Run the console in under 5 minutes | [Quick Start](./quick-start.md) |
+| Publish your first reverse proxy configuration | [Publish First Configuration](./first-site.md) |
+| Configure intranet penetration mapping | [Tunnel & Intranet Penetration](./tunnel-usage.md) |
+| Configure CC protection & IP group blocking | [WAF Security Protection](./waf-usage.md) |
+| Write auto IP group aggregation rules | [WAF Auto IP Group Expressions](./waf-ip-group-expr.md) |
+| Connect or reinstall a node Agent | [Access Agent](../deployment/agent.md) |
+| Start Server from source code | [Launch Server](../deployment/server.md) |
+| Configure GitHub or OIDC SSO | [SSO Login Configuration](./sso.md) |
+| Upgrade Server or Agent | [Upgrade & Maintenance](../deployment/upgrade.md) |
+| Participate in development or bug fixing | [Local Development](../design/development.md) and [Development Constraints](../../guideline/Constraints.md) |
+| Understand architecture and publishing | [System Architecture](../design/architecture.md) and [Agent & Publish Model](../design/agent-design.md) |
+| View open-source references and credits | [Credits](./credits.md) |
+
+## Documentation Partitions
+
+`guide/` is oriented toward users and deployers, providing actionable steps from installation to daily operations.
+
+`reference/` collects stable facts such as configuration fields, commands, API response structures, and repository layout.
+
+`design/` is oriented toward maintainers and contributors, describing product boundaries, system architecture, Agent & publishing models, and engineering constraints. Before adding capabilities or changing boundaries, update the corresponding design document first.