feat: add GET / route returning info response

Maps root path to the existing info_handler so the service
returns a 200 with version info instead of 404.

crates/kreuzberg/src/api/router.rs

@@ -167,6 +167,7 @@ pub(crate) fn create_router_with_limits_and_server_config(
     };
 
     let mut router = Router::new()
+        .route("/", get(info_handler))
         .route("/extract", post(extract_handler))
         .route("/extract-structured", post(extract_structured_handler))
         .route("/extract-async", post(extract_async_handler))