onboarding: remove AsciiAnimation decoration and 'by ELYDORA' signatures (P1-17, P1-18); move hero-drift keyframes to global CSS (P3-60)

src/renderer/styles.css

@@ -792,14 +792,10 @@ a.paperclip-project-mention-chip {
   -webkit-app-region: no-drag;
 }
 
-/* ASCII animation */
-@keyframes ascii-scroll-up {
-  0% { transform: translateY(0); }
-  100% { transform: translateY(-50%); }
-}
-
-.ascii-scroll-track {
-  animation: ascii-scroll-up 80s linear infinite;
+/* Onboarding hero ambient drift */
+@keyframes hero-drift {
+  0% { transform: translate(0, 0) scale(1); }
+  100% { transform: translate(-4%, 3%) scale(1.05); }
 }
 
 @media (prefers-reduced-motion: reduce) {