fix(server): 健康检查和 OpenAPI 端点移出限流中间件范围

account_lockout_middleware 改为 fail-close 后，/health 和 /docs/openapi.json
不应受影响。将它们提取为 unthrottled_routes 独立层。

crates/erp-server/src/main.rs

@@ -503,12 +503,7 @@ async fn main() -> anyhow::Result<()> {
     // Layer execution order (outer → inner): account_lockout → rate_limit_by_ip
     // So account lockout check runs FIRST, then IP rate limiting
     let public_routes = Router::new()
-        .merge(handlers::health::health_check_router())
         .merge(erp_auth::AuthModule::public_routes())
-        .route(
-            "/docs/openapi.json",
-            axum::routing::get(handlers::openapi::openapi_spec),
-        )
         .layer(axum::middleware::from_fn_with_state(
             state.clone(),
             middleware::rate_limit::account_lockout_middleware,
@@ -519,6 +514,15 @@ async fn main() -> anyhow::Result<()> {
         ))
         .with_state(state.clone());
 
+    // Unthrottled public routes (health, docs) — no rate limiting
+    let unthrottled_routes = Router::new()
+        .merge(handlers::health::health_check_router())
+        .route(
+            "/docs/openapi.json",
+            axum::routing::get(handlers::openapi::openapi_spec),
+        )
+        .with_state(state.clone());
+
     // Clone jwt_secret for upload auth before protected_routes closure moves it
     let secret_for_uploads = jwt_secret.clone();
 
@@ -577,7 +581,7 @@ async fn main() -> anyhow::Result<()> {
             async move { upload_auth_middleware(secret, req, next).await }
         }));
     let app = Router::new()
-        .nest("/api/v1", public_routes.merge(protected_routes))
+        .nest("/api/v1", unthrottled_routes.merge(public_routes).merge(protected_routes))
         .nest("/uploads", uploads_router)
         .layer(cors);