fix(frontend): maximum amount of brains reached (#2323)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

frontend/lib/components/AddBrainModal/components/CreateBrainStep/hooks/useBrainCreationApi.ts

@@ -1,4 +1,5 @@
 import { useMutation, useQueryClient } from "@tanstack/react-query";
+import { AxiosError } from "axios";
 import { UUID } from "crypto";
 import { useState } from "react";
 import { useFormContext } from "react-hook-form";
@@ -92,11 +93,18 @@ export const useBrainCreationApi = () => {
         text: t("brainCreated", { ns: "brain" }),
       });
     },
-    onError: () => {
-      publish({
-        variant: "danger",
-        text: t("errorCreatingBrain", { ns: "brain" }),
-      });
+    onError: (error: AxiosError) => {
+      if (error.response && error.response.status === 429) {
+        publish({
+          variant: "danger",
+          text: "You have reached your maximum amount of brains. Upgrade your plan to create more.",
+        });
+      } else {
+        publish({
+          variant: "danger",
+          text: t("errorCreatingBrain", { ns: "brain" }),
+        });
+      }
     },
   });