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/KeyGate.tsx

@@ -93,7 +93,7 @@ export default function KeyGate({ meId, compact = false }: { meId: number; compa
     return (
       <div className={`glass rounded-2xl space-y-3 ${compact ? "p-3" : "p-4"}`}>
         <div className="flex items-center gap-2">
-          <AlertTriangle className="w-5 h-5 text-red-400 shrink-0" />
+          <AlertTriangle className="w-5 h-5 text-danger shrink-0" />
           <div className="font-semibold text-sm">{t("messages.resetTitle")}</div>
         </div>
         <p className="text-sm text-muted">{t("messages.resetWarn")}</p>
@@ -107,7 +107,7 @@ export default function KeyGate({ meId, compact = false }: { meId: number; compa
             className={inputCls}
           />
         )}
-        {err && <div className="text-sm text-red-400">{err}</div>}
+        {err && <div className="text-sm text-danger">{err}</div>}
         <div className="flex gap-2">
           <button
             onClick={cancelReset}
@@ -119,7 +119,7 @@ export default function KeyGate({ meId, compact = false }: { meId: number; compa
           <button
             onClick={doReset}
             disabled={busy}
-            className="inline-flex items-center gap-2 px-4 py-2 rounded-xl font-semibold bg-red-500/90 text-white hover:bg-red-500 transition disabled:opacity-40"
+            className="inline-flex items-center gap-2 px-4 py-2 rounded-xl font-semibold bg-danger/90 text-danger-fg hover:bg-danger transition disabled:opacity-40"
           >
             <AlertTriangle className="w-4 h-4" />
             {t("messages.resetButton")}
@@ -158,7 +158,7 @@ export default function KeyGate({ meId, compact = false }: { meId: number; compa
           className={inputCls}
         />
       )}
-      {err && <div className="text-sm text-red-400">{err}</div>}
+      {err && <div className="text-sm text-danger">{err}</div>}
       <button
         onClick={submit}
         disabled={busy || !pass}