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/VideoCard.tsx

@@ -156,7 +156,7 @@ function RowMetaCells({ video }: { video: Video }) {
   // "live" dot and a "stream" dot would be the same dot.
   const status =
     video.live_status === "live"
-      ? { Icon: Radio, cls: "text-red-500", label: t("card.live") }
+      ? { Icon: Radio, cls: "text-danger", label: t("card.live") }
       : video.live_status === "upcoming"
         ? { Icon: Clock, cls: "", label: t("card.upcoming") }
         : video.live_status === "was_live"
@@ -250,7 +250,7 @@ function Thumb({
       ) : video.live_status === "live" || video.live_status === "upcoming" ? (
         <span
           className={`absolute bottom-1.5 right-1.5 text-[10px] font-semibold uppercase tracking-wide px-1.5 py-0.5 rounded ${
-            video.live_status === "live" ? "bg-red-500/90 text-white" : "bg-black/80 text-white"
+            video.live_status === "live" ? "bg-danger/90 text-danger-fg" : "bg-black/80 text-white"
           }`}
         >
           {t(`card.${video.live_status}`)}