refactor(ui): simplify and polish insight card components

Replace hardcoded hex color values with Dracula CSS var tokens
(text-dracula-purple, text-dracula-green, etc.) for theme consistency.
Add prefers-reduced-motion support for insight animations, aria-expanded
on the data quality toggle, and extract nested ternary into lookup map.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/globals.css

@@ -182,3 +182,9 @@
 .animate-insight-in {
   animation: insight-fade-in 0.4s ease-out forwards;
 }
+
+@media (prefers-reduced-motion: reduce) {
+  .animate-insight-in {
+    animation: none;
+  }
+}