fix: fix Docker dev proxy and handle non-JSON error responses in frontend

packages/web/src/lib/api.ts

@@ -66,7 +66,13 @@ export async function apiFetch<T>(path: string, options: RequestInit = {}): Prom
     }
   }
 
-  const json: ApiResponse<T> = await res.json();
+  const text = await res.text();
+  let json: ApiResponse<T>;
+  try {
+    json = JSON.parse(text);
+  } catch {
+    throw new Error(`Server error (${res.status})`);
+  }
   if (!json.success) {
     throw new Error(json.error?.message || 'Request failed');
   }