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/ui/Badge.tsx

@@ -1,6 +1,6 @@
 const variantStyles: Record<string, string> = {
   auto: 'bg-blue-500/15 text-blue-400 border-blue-500/20',
-  manual: 'bg-violet-500/15 text-violet-400 border-violet-500/20',
+  manual: 'bg-sky-500/15 text-sky-400 border-sky-500/20',
   default: 'bg-white/[0.06] text-gray-400 border-white/[0.08]',
 };