feat(theme): R10 S1 — semantic status colors (danger/warn/success)

Add theme-scoped --danger/--warn/--success (+ -fg) tokens wired into the v4
@theme inline, replacing ~110 raw red/amber/emerald/green palette refs across
34 files. Fixes light-theme contrast failures (fixed Tailwind shades fell to
~1.7-3:1 on white). Status colors are scheme-independent — recognised by hue,
shifting only by theme to hold contrast (bright on dark bg, darkened on light).
Solid fills use the paired -fg text; @source inline guarantees the full -fg set
exists. IMDb rating gold kept as a deliberate decorative non-status exception.

frontend/src/components/OnboardingWizard.tsx

@@ -20,8 +20,8 @@ import Overlay from "./Overlay";
 // A small reusable heads-up so the Google consent warning never feels like a surprise.
 function ConsentHeadsUp() {
   return (
-    <div className="flex gap-2.5 rounded-xl border border-amber-400/30 bg-amber-400/5 p-3 text-left">
-      <AlertTriangle className="w-4 h-4 shrink-0 mt-0.5 text-amber-400" />
+    <div className="flex gap-2.5 rounded-xl border border-warn/30 bg-warn/5 p-3 text-left">
+      <AlertTriangle className="w-4 h-4 shrink-0 mt-0.5 text-warn" />
       <p className="text-xs leading-relaxed text-fg/80">
         <Trans
           i18nKey="onboarding.consent"