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/Banner.tsx

@@ -11,9 +11,9 @@ const TONES: Record<BannerTone, { bar: string; icon: string; action: string }> =
     action: "bg-accent text-accent-fg",
   },
   warning: {
-    bar: "bg-amber-500/15 border-amber-500/30",
-    icon: "text-amber-500",
-    action: "bg-amber-500 text-black",
+    bar: "bg-warn/15 border-warn/30",
+    icon: "text-warn",
+    action: "bg-warn text-warn-fg",
   },
 };