fix: lower sidebar breakpoint from md to sm so desktop sidebar renders

Responsive variants (md:flex, md:hidden) were silently missing from the
Tailwind CSS bundle due to stale build cache — sidebar was always hidden.
Changed breakpoint to sm (640px) and use rm -rf .next before builds.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CPf5Rc8QPx6V8KLEEgfKEQ

app/(protected)/layout.tsx

@@ -29,7 +29,7 @@ export default async function ProtectedLayout({
         userName={profile?.name ?? user.email ?? ''}
         userEmail={profile?.email ?? user.email ?? ''}
       />
-      <div className="md:ml-60 pb-16 md:pb-0">
+      <div className="sm:ml-60 pb-16 sm:pb-0">
         {children}
       </div>
     </div>