fix: remove 'Закрыть' button from success popup — X button is enough

src/components/ui/SignupModal.tsx

@@ -181,12 +181,6 @@ export function SignupModal({
                 {subtitle && <p className="mt-1 text-sm text-neutral-400">{subtitle}</p>}
               </>
             )}
-            <button
-              onClick={handleClose}
-              className="mt-6 rounded-full bg-gold px-6 py-2.5 text-sm font-semibold text-black transition-all hover:bg-gold-light cursor-pointer"
-            >
-              Закрыть
-            </button>
           </div>
         ) : error === "network" ? (
           /* Network error — fallback to Instagram DM */