fix: Set Vercel output directory to static/admin and update deployment documentation to clarify this configuration.

DEPLOY.en.md

@@ -132,6 +132,21 @@ Another common root cause (Go monorepo + `internal/`):
 This usually happens when the Vercel Go entrypoint imports `internal/...` directly.
 This repo now avoids that by using a public bridge package: `api/index.go` -> `ds2api/app` -> `internal/server`.
 
+If you see:
+
+```text
+No Output Directory named "public" found after the Build completed.
+```
+
+Vercel is validating frontend output against `public`, while this repo emits WebUI assets to `static/admin`.
+`vercel.json` now explicitly sets:
+
+```json
+"outputDirectory": "static/admin"
+```
+
+If you manually changed Output Directory in Project Settings, set it to `static/admin` (or clear it and let repo config apply).
+
 ## 4. Reverse Proxy (Nginx)
 
 Disable buffering for SSE:

DEPLOY.md

@@ -131,6 +131,20 @@ Error: Command failed: go build -ldflags -s -w -o .../bootstrap .../main__vc__go
 这通常发生在 Vercel Go 入口文件直接 `import internal/...`。
 当前仓库已通过公开桥接包 `app` 解决：`api/index.go` -> `ds2api/app` -> `internal/server`。
 
+若看到类似报错：
+
+```text
+No Output Directory named "public" found after the Build completed.
+```
+
+说明 Vercel 正在按 `public` 校验前端产物目录。当前仓库前端产物目录是 `static/admin`，已在 `vercel.json` 显式配置：
+
+```json
+"outputDirectory": "static/admin"
+```
+
+若你在项目设置里手动改过 Output Directory，请同步改为 `static/admin` 或清空让仓库配置生效。
+
 ## 4. 反向代理（Nginx）
 
 如果在 Nginx 后挂载，建议关闭缓冲以保证 SSE：

vercel.json

@@ -1,6 +1,7 @@
 {
   "version": 2,
   "buildCommand": "npm ci --prefix webui && npm run build --prefix webui",
+  "outputDirectory": "static/admin",
   "functions": {
     "api/index.go": {
       "includeFiles": "static/admin/**"