refinement phase 4

client/src/lib/api/client.ts

@@ -36,9 +36,13 @@ export async function clientFetch<T>(path: string, options?: RequestInit, isRetr
   const locale = window.location.pathname.split('/')[1] || 'fa';
 
   const reqHeaders: Record<string, string> = {
-    'Content-Type': 'application/json',
     'Accept-Language': locale,
   };
+  // Let the browser set `Content-Type` (with the multipart boundary) for FormData bodies — a manual
+  // JSON content-type there breaks the upload. JSON bodies still declare it explicitly.
+  if (!(options?.body instanceof FormData)) {
+    reqHeaders['Content-Type'] = 'application/json';
+  }
   if (token) {
     reqHeaders['Authorization'] = `Bearer ${token}`;
   }