fix: add fallbackRedirectUrl to auth pages

Clerk dashboard settings were overriding env vars, causing redirect
to /login (404) after sign-in. Added explicit fallbackRedirectUrl
prop to SignIn and SignUp components to ensure redirect to /dashboard.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: MuhsinunC

src/app/sign-in/[[...sign-in]]/page.tsx

@@ -4,6 +4,7 @@ export default function SignInPage() {
   return (
     <div className="flex min-h-screen items-center justify-center bg-gray-50 dark:bg-gray-900">
       <SignIn
+        fallbackRedirectUrl="/dashboard"
         appearance={{
           elements: {
             rootBox: 'mx-auto',

src/app/sign-up/[[...sign-up]]/page.tsx

@@ -4,6 +4,7 @@ export default function SignUpPage() {
   return (
     <div className="flex min-h-screen items-center justify-center bg-gray-50 dark:bg-gray-900">
       <SignUp
+        fallbackRedirectUrl="/dashboard"
         appearance={{
           elements: {
             rootBox: 'mx-auto',