Add product review model, serializer, and API endpoint

Introduces a Review model for product reviews, including rating and comment fields. Adds a public serializer and a ModelViewSet for reviews with search and ordering capabilities. Also updates the frontend API client to use the correct token refresh endpoint and improves FormData handling.

frontend/src/api/privateClient.ts

@@ -22,7 +22,7 @@ privateApi.interceptors.response.use(
       original._retry = true;
 
       try {
-        await privateApi.post("/auth/refresh/");
+        await privateApi.post("/api/account/token/refresh/");
         return privateApi(original);
       } catch {
         // optional: logout
@@ -37,6 +37,11 @@ privateApi.interceptors.response.use(
 export const privateMutator = async <T>(
   config: AxiosRequestConfig
 ): Promise<T> => {
+  // If sending FormData, remove Content-Type header to let axios set it with boundary
+  if (config.data instanceof FormData) {
+    delete config.headers?.['Content-Type'];
+  }
+  
   const response = await privateApi.request<T>(config);
   return response.data;
 };