fix: make vercel go entrypoint internal-safe

DEPLOY.en.md

@@ -113,6 +113,15 @@ How to fix:
 4. Ensure `go.mod` uses a supported version (this repo uses `go 1.24`)
 5. Redeploy (preferably with cache cleared)
 
+Another common root cause (Go monorepo + `internal/`):
+
+```text
+... use of internal package ds2api/internal/server not allowed
+```
+
+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`.
+
 ## 4. Reverse Proxy (Nginx)
 
 Disable buffering for SSE:

DEPLOY.md

@@ -112,6 +112,15 @@ Error: Command failed: go build -ldflags -s -w -o .../bootstrap .../main__vc__go
 4. 确认仓库 `go.mod` 为受支持版本（当前为 `go 1.24`）
 5. 重新部署（建议 `Redeploy` 并清缓存）
 
+另一个常见根因（Go 单仓 + `internal/`）：
+
+```text
+... use of internal package ds2api/internal/server not allowed
+```
+
+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`。
+
 ## 4. 反向代理（Nginx）
 
 如果在 Nginx 后挂载，建议关闭缓冲以保证 SSE：

api/index.go

@@ -4,17 +4,17 @@ import (
 	"net/http"
 	"sync"
 
-	"ds2api/internal/server"
+	"ds2api/app"
 )
 
 var (
 	once sync.Once
-	app  *server.App
+	h    http.Handler
 )
 
 func Handler(w http.ResponseWriter, r *http.Request) {
 	once.Do(func() {
-		app = server.NewApp()
+		h = app.NewHandler()
 	})
-	app.Router.ServeHTTP(w, r)
+	h.ServeHTTP(w, r)
 }

app/handler.go

@@ -0,0 +1,11 @@
+package app
+
+import (
+	"net/http"
+
+	"ds2api/internal/server"
+)
+
+func NewHandler() http.Handler {
+	return server.NewApp().Router
+}