Fix red border on account signup

Applied inline red border and hover styling to the Skapa konto button:
- Replaced Tailwind border classes with an explicit 2px red border (#dc2626)
- Ensured hover/focus states use a semi-transparent red background (rgba(220,38,38,0.3))
- Adjusted to preserve button layout within AccountMenu.tsx

X-Lovable-Edit-ID: edt-e64d77b3-1ce1-4050-8b07-9e67c2684235

src/components/AccountMenu.tsx

@@ -61,7 +61,8 @@ const AccountMenu = () => {
               <div className="px-1 py-1">
                 <button
                   onClick={() => handleOpenAuth("signup")}
-                  className="w-full px-3 py-2 text-left font-bold border-2 border-red-600 rounded-md hover:bg-red-600/30 transition-colors"
+                  className="w-full px-3 py-2 text-left font-bold rounded-md hover:bg-[rgba(220,38,38,0.3)] focus:bg-[rgba(220,38,38,0.3)] transition-colors"
+                  style={{ border: '2px solid #dc2626' }}
                 >
                   Skapa konto
                 </button>