RedirectToSignIn not respecting publishableKey passed to authMiddleware
## Context
Passing publishableKey explicitly to authMiddleware (custom env var naming) works, but calling redirectToSignIn inside afterAuth throws 'Missing publishableKey'.
## Verified resolution
Maintainer brkalow: addressed in recent versions - keys passed to clerkMiddleware() are now respected by the auth methods called inside the middleware handler; see the dynamic-keys docs. Workaround used in the thread: inject the key into process.env.CLERK_PUBLISHABLE_KEY before the middleware runs.