UI/UX redesign: unified refined-glass design system

- Add shared UI primitives: Button, Field/Input/Select, PageHeader,
  Section, Callout, Tabs, Disclosure
- Replace gradient buttons with single blue-accent btn-primary
- Reserve gradient text for the brand wordmark only
- Rework Scanner page onto the glass system; collapse explainer and
  glossary into a disclosure, move filters into a glass toolbar
- Restructure Ticker Detail into tabs (Analysis / Indicators / S/R)
  with chart and recommendation always visible
- Align Watchlist, Rankings, Admin, Login/Register to shared primitives
- Unify stray indigo/violet/gray accents into the blue family

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/admin/TickerUniverseBootstrap.tsx

@@ -78,7 +78,7 @@ export function TickerUniverseBootstrap() {
 
       <div className="flex flex-wrap gap-2">
         <button
-          className="btn-gradient px-4 py-2 text-sm disabled:opacity-50"
+          className="btn-primary px-4 py-2 text-sm disabled:opacity-50"
           onClick={onSaveDefault}
           disabled={isLoading || updateDefault.isPending || bootstrap.isPending}
         >