refactor(theming): replace red-* palette with semantic error-* tokens

Sweep 30 files: text/bg/border/ring/from/to/via/fill/stroke/shadow/divide/decoration/
outline/placeholder-red-N → -error-N. All red usages were semantically error/danger
(no brand red), so tokens now flow through the design-system CSS variables and respond
to palette overrides.

src/components/connection/TvQuickConnect.tsx

@@ -323,7 +323,7 @@ export default function TvQuickConnect({ subscriptionUrl, isLight }: Props) {
       {toast && (
         <div
           className={`fixed bottom-6 left-1/2 z-50 -translate-x-1/2 rounded-xl px-5 py-3 text-sm font-medium shadow-lg transition-all ${
-            toast.type === 'success' ? 'bg-emerald-500/90 text-white' : 'bg-red-500/90 text-white'
+            toast.type === 'success' ? 'bg-emerald-500/90 text-white' : 'bg-error-500/90 text-white'
           }`}
         >
           {toast.text}