Fix: Clerk redirect

[njdowdy]

Clerk was giving me a 404 on redirect to '/' (and other routes) after trying to use OAuth.

The fix was to change the folder structure for Clerk sign-in and sign-up to include a catch-all segment.

The following replacements needed to be made:
src/app/sign-in/page.tsx -> src/app/sign-in/[[...sign-in]]/page.tsx
src/app/sign-up/page.tsx -> src/app/sign-up/[[...sign-up]]/page.tsx

See the Clerk quick start for more info: https://clerk.com/docs/quickstarts/nextjs#build-your-sign-in-page

[nicoalbanese]

Thanks - have updated