Horizon redesign: space theme, visual dashboard, chart reskin

Replaces the citron/green glass theme with the Horizon direction
(mockup at /design-horizon): space-void background, starfield, dim
Mars horizon, rim-cyan accent, rose for negative. Palette validated
for CVD separation and contrast on the dark surface.

- tailwind.config: gray -> cool space neutrals, blue/emerald -> cyan
  scale, red -> rose; display font Space Grotesk
- globals.css: Horizon tokens, atmosphere, denser glass, cyan
  buttons/inputs, price-rail / R-bar / radar chart CSS
- Dashboard rebuilt: verdict hero, top-pick card with spatial price
  rail, KPI tiles, open positions as diverging R-bars with expandable
  detail + trade chart (OHLCV since entry, entry/stop/target levels),
  radar list with per-setup disqualify reason, watchlist chips
- OpenTradesPanel: table replaced by R-bar rows; all fields kept in
  the drill-down (shares, P&L, alpha, trailing stop, sell)
- qualification: disqualifyReason() mirrors qualifiesSetup rule order
- CandlestickChart: canvas colors moved to Horizon palette; S/R now
  cyan/neutral so rose stays reserved for the stop level
- ScoreCard: radar score fingerprint with hover values
- Design mockup pages included (routed in App.tsx)

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

frontend/src/components/layout/AppShell.tsx

@@ -5,6 +5,10 @@ import MobileNav from './MobileNav';
 export default function AppShell() {
   return (
     <div className="flex min-h-screen text-gray-100">
+      <div className="app-horizon" aria-hidden="true">
+        <div className="app-horizon-rim" />
+        <div className="app-horizon-planet" />
+      </div>
       <Sidebar />
       <div className="flex-1 flex flex-col">
         <MobileNav />