fix: _sign request on hf spaces

frontend/src/api.ts

@@ -11,7 +11,15 @@ import type {
   ContextAnalysisResponse,
 } from "./types";
 
-const client = axios.create({ baseURL: "/api" });
+// HuggingFace Spaces proxy requires the __sign token on every request.
+// Extract it from the page URL and attach to all API calls.
+const _params = new URLSearchParams(window.location.search);
+const _sign = _params.get("__sign");
+
+const client = axios.create({
+  baseURL: "/api",
+  ...(_sign && { params: { __sign: _sign } }),
+});
 const long = { timeout: 600000 };
 
 /** Extract a human-readable error message from an Axios error. */