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/PlexInfo.tsx

@@ -188,6 +188,7 @@ export default function PlexInfo({
                   </Filterable>
                 )}
                 {detail.imdb_rating != null && (
+                  // decorative rating gold — intentionally NOT a status token
                   <span className="inline-flex items-center gap-1 rounded-md bg-amber-400/15 px-1.5 py-0.5 font-semibold text-amber-500">
                     <button
                       onClick={