Fix WCAG AA color contrast violations across all pages

Replace incorrect perceived-brightness formula in Stats progress bars
with proper WCAG relative luminance calculation, and convert type bar
colors to hex values for reliable contrast detection. Add light: variant
classes to status badges, yellow/purple text, and admin nav links across
17 files. Darken light-mode status-active token and text-tertiary/muted
tokens. Add aria-labels to admin filter selects and flex-wrap for mobile
overflow on AdminEvolutions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/admin/AdminGames.tsx

@@ -70,8 +70,9 @@ export function AdminGames() {
         </div>
       </div>
 
-      <div className="mb-4 flex items-center gap-4">
+      <div className="mb-4 flex flex-wrap items-center gap-4">
         <select
+          aria-label="Filter by region"
           value={regionFilter}
           onChange={(e) => setRegionFilter(e.target.value)}
           className="px-3 py-2 border rounded-md bg-surface-2 border-border-default"
@@ -84,6 +85,7 @@ export function AdminGames() {
           ))}
         </select>
         <select
+          aria-label="Filter by generation"
           value={genFilter}
           onChange={(e) => setGenFilter(e.target.value)}
           className="px-3 py-2 border rounded-md bg-surface-2 border-border-default"