Stop treating login/save-progress as a 48-character email limit.

The overlay was failing Zod on preset method-card support text attached with the draft; raise that cap, allow RFC-length emails, and drop Back to home from the overlay.

Co-authored-by: Cursor <cursoragent@cursor.com>

stories/modals/Login.stories.tsx

@@ -95,7 +95,7 @@ export const HeaderOverlayBlurred = {
     docs: {
       description: {
         story:
-          'Same as **Log in** from the site header: `backdropVariant="blurredYellow"`, `usePortal`, card + “Back to home” below.',
+          'Same as **Log in** from the site header: `backdropVariant="blurredYellow"`, `usePortal`, no “Back to home” under the card.',
       },
     },
   },
@@ -107,14 +107,6 @@ export const HeaderOverlayBlurred = {
         backdropVariant="blurredYellow"
         usePortal
         ariaLabelledBy="login-modal-heading"
-        belowCard={
-          <a
-            href="/"
-            className="text-center text-small-paragraph text-[var(--color-content-invert-tertiary)] hover:opacity-90"
-          >
-            {backToHome}
-          </a>
-        }
       >
         <Suspense fallback={<p className="p-6 text-small-paragraph">Loading…</p>}>
           <LoginForm />