Simplify modal, badge, and component styles to dark-first (#29)

Co-authored-by: Julian Tabel <juliantabel.jt@gmail.com>
Co-committed-by: Julian Tabel <juliantabel.jt@gmail.com>

frontend/src/components/RuleBadges.tsx

@@ -20,10 +20,10 @@ export function RuleBadges({ rules }: RuleBadgesProps) {
           title={def.description}
           className={`px-2 py-0.5 rounded-full text-xs font-medium ${
             def.category === 'core'
-              ? 'bg-blue-100 text-blue-800 dark:bg-blue-900/40 dark:text-blue-300'
+              ? 'bg-blue-900/40 text-blue-300'
               : def.category === 'completion'
-                ? 'bg-green-100 text-green-800 dark:bg-green-900/40 dark:text-green-300'
-                : 'bg-amber-100 text-amber-800 dark:bg-amber-900/40 dark:text-amber-300'
+                ? 'bg-green-900/40 text-green-300'
+                : 'bg-amber-900/40 text-amber-300'
           }`}
         >
           {def.name}