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/PlayerModal.tsx

@@ -1077,7 +1077,7 @@ export default function PlayerModal({
             {playerError != null && (
               <div className="absolute inset-0 grid place-items-center bg-bg p-6 text-center">
                 <div className="max-w-sm">
-                  <AlertTriangle className="w-8 h-8 text-amber-500 mx-auto mb-3" />
+                  <AlertTriangle className="w-8 h-8 text-warn mx-auto mb-3" />
                   <h3 className="text-base font-semibold">{t("player.unavailableTitle")}</h3>
                   <p className="text-sm text-muted mt-1.5 mb-4">
                     {playerError === 101 || playerError === 150