fix: fall back to ChuRepo for release installation and updates

README.md

@@ -20,7 +20,11 @@ ChuSQL 是采用 Haskell SQL 引擎与 Rust 存储层的数据库项目，提供
 Linux / macOS：
 
 ```sh
-curl -fsSL https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.sh | sh -s -- --component web
+(curl -fsSL --connect-timeout 10 \
+  https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.sh -o install.sh ||
+ curl -fsSL --connect-timeout 10 \
+  https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.sh -o install.sh) &&
+sh install.sh --component web
 ```
 
 也可从 ChuRepo 下载后执行：
@@ -35,7 +39,11 @@ sh install.sh --component web
 Windows（PowerShell 里下下来再跑；也有下载 zip 解压的包内安装）：
 
 ```powershell
-irm https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.ps1 -OutFile "$env:TEMP\install.ps1"
+try {
+    irm https://raw.githubusercontent.com/TheBadRoger/ChuSQL/main/scripts/install.ps1 -OutFile "$env:TEMP\install.ps1" -TimeoutSec 60 -ErrorAction Stop
+} catch {
+    irm https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.ps1 -OutFile "$env:TEMP\install.ps1" -TimeoutSec 60 -ErrorAction Stop
+}
 & "$env:TEMP\install.ps1" -Component web
 ```
 
@@ -46,7 +54,7 @@ irm https://repo.chunana.cn/ChuNa7a/ChuSQL/raw/branch/main/scripts/install.ps1 -
 & "$env:TEMP\install.ps1" -Component web
 ```
 
-以上在线安装脚本默认从 GitHub 获取发行包，脚本下载来源不会改变发行包来源。GitHub 不可用时，参见[包内安装](docs/install.md#包内安装)或[从源码安装](docs/install.md#从源码安装)。
+上述命令下载脚本时优先 GitHub，失败后尝试 ChuRepo。脚本安装和更新时也会自动回退：版本查询或发行包下载失败时尝试 ChuRepo；已选定的版本保持不变，校验失败直接报错。两站均无对应发行包时需使用包内安装或源码安装。显式指定其他仓库或归档 URL 时不会回退到官方仓库。
 
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