fix(frontend): next step impossible if no knowledge when creating brain if no onboarded (#2688)

# 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/BrainRecapStep/BrainRecapStep.tsx

@@ -124,11 +124,6 @@ export const BrainRecapStep = (): JSX.Element => {
             await feed();
             setIsBrainCreated(true);
           }}
-          disabled={
-            knowledgeToFeed.length === 0 &&
-            !userIdentityData?.onboarded &&
-            !openedConnections.length
-          }
           isLoading={creating}
           important={true}
         />

frontend/lib/components/AddBrainModal/components/FeedBrainStep/FeedBrainStep.tsx

@@ -5,6 +5,7 @@ import { useFromConnectionsContext } from "@/app/chat/[chatId]/components/Action
 import { OpenedConnection } from "@/lib/api/sync/types";
 import { MessageInfoBox } from "@/lib/components/ui/MessageInfoBox/MessageInfoBox";
 import QuivrButton from "@/lib/components/ui/QuivrButton/QuivrButton";
+import { useKnowledgeToFeedContext } from "@/lib/context/KnowledgeToFeedProvider/hooks/useKnowledgeToFeedContext";
 import { createHandleGetButtonProps } from "@/lib/helpers/handleConnectionButtons";
 import { useUserData } from "@/lib/hooks/useUserData";
 
@@ -25,6 +26,7 @@ export const FeedBrainStep = (): JSX.Element => {
   const [currentConnection, setCurrentConnection] = useState<
     OpenedConnection | undefined
   >(undefined);
+  const { knowledgeToFeed } = useKnowledgeToFeedContext();
 
   useEffect(() => {
     setCurrentConnection(
@@ -96,6 +98,11 @@ export const FeedBrainStep = (): JSX.Element => {
             iconName="chevronRight"
             onClick={goToNextStep}
             important={true}
+            disabled={
+              knowledgeToFeed.length === 0 &&
+              !userIdentityData?.onboarded &&
+              !openedConnections.length
+            }
           />
         )}
       </div>