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/SyncStatus.tsx

@@ -83,7 +83,7 @@ export default function SyncStatus({
     </span>
   ) : (
     // A small check anchors the "all synced" state so it doesn't read as orphaned text.
-    <span className="flex items-center gap-1 text-emerald-500">
+    <span className="flex items-center gap-1 text-success">
       <CheckCircle2 className="w-3.5 h-3.5" />
       <span className="text-muted">{t("header.sync.allSynced")}</span>
     </span>