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/Toaster.tsx

@@ -5,10 +5,10 @@ import { dismiss, getActiveToasts, subscribe, type NotifLevel } from "../lib/not
 
 export const LEVEL_STYLE: Record<NotifLevel, { icon: typeof Info; color: string; bar: string }> = {
   info: { icon: Info, color: "text-accent", bar: "bg-accent" },
-  success: { icon: CheckCircle2, color: "text-emerald-400", bar: "bg-emerald-400" },
-  warning: { icon: AlertTriangle, color: "text-amber-400", bar: "bg-amber-400" },
-  error: { icon: AlertCircle, color: "text-red-400", bar: "bg-red-400" },
-  fatal: { icon: XCircle, color: "text-red-500", bar: "bg-red-500" },
+  success: { icon: CheckCircle2, color: "text-success", bar: "bg-success" },
+  warning: { icon: AlertTriangle, color: "text-warn", bar: "bg-warn" },
+  error: { icon: AlertCircle, color: "text-danger", bar: "bg-danger" },
+  fatal: { icon: XCircle, color: "text-danger", bar: "bg-danger" },
 };
 
 export default function Toaster() {