feat(auth): 完善英文初始化与裸机安装

在登录和首个管理员创建前提供中英文切换，并在初始化状态不可达时展示可重试错误，避免误入登录页。

对齐源码构建产物与安装脚本路径，增加 systemd/API 就绪检查、失败诊断及中英文裸机文档。

Closes #104

docs-site/docs/getting-started/installation.md

@@ -55,10 +55,11 @@ sudo ./install.sh        # creates system user, installs to /opt/backupx, sets u
 The installer:
 
 1. Creates a `backupx` system user
-2. Installs binary to `/opt/backupx/backupx`
-3. Creates `/opt/backupx/config.yaml` with safe defaults
+2. Installs the binary to `/opt/backupx/bin/backupx` and the web console to `/opt/backupx/web`
+3. Creates `/etc/backupx/config.yaml` with safe defaults
 4. Installs and enables the `backupx.service` systemd unit
 5. (Optional) Configures an Nginx reverse proxy
+6. Waits for `/api/auth/setup/status`; if startup fails, prints systemd diagnostics and exits non-zero
 
 ## From source
 
@@ -67,16 +68,17 @@ Requires Go ≥ 1.25 and Node.js ≥ 20.
 ```bash
 git clone https://github.com/Awuqing/BackupX.git && cd BackupX
 make build
-# or, for builds behind the great firewall
-make docker-cn
+sudo ./deploy/install.sh
 ```
 
 After `make build`, the binary is at `server/bin/backupx` and the built web UI is at `web/dist/`.
+The installer consumes those exact paths, so no Docker runtime is required. If an existing configuration uses a non-default port, set `HEALTH_URL` for the readiness check, for example `sudo HEALTH_URL=http://127.0.0.1:9000/api/auth/setup/status ./deploy/install.sh`.
 
 ## Verify the install
 
 ```bash
-backupx --version           # e.g. v1.6.0
+/opt/backupx/bin/backupx --version
+curl -fsS http://127.0.0.1:8340/api/auth/setup/status
 ```
 
-Then open `http://your-server:8340` to see the initial admin setup screen.
+Then open `http://your-server:8340`. Choose **English** or **中文** in the upper-right corner. A fresh database shows **System setup**, where you create the first administrator username and password. If that form does not appear, retry the status request above before attempting to sign in.