feat(design): Matrix toned down to moss, text on an accent fill held to --accent-fg

The lime accent was the loudest of the four (OKLCH L 0.85, C 0.21) and read as neon; the owner chose the
moss variant at Midnight's lightness with near-neutral greys, and the Matrix backdrops follow it. Fixed
white/black parts on a solid accent fill (two switch knobs, three play buttons, the Up next pill) now use
--accent-fg, and theme.contract.test.ts refuses a fixed white or black next to a solid bg-accent.

frontend/src/components/PlexInfo.tsx

@@ -594,7 +594,7 @@ export default function PlexInfo({
                   {onPlay && (
                     <button
                       onClick={onPlay}
-                      className="inline-flex items-center gap-2 rounded-xl bg-accent px-4 py-2 font-medium text-white hover:opacity-90"
+                      className="inline-flex items-center gap-2 rounded-xl bg-accent px-4 py-2 font-medium text-accent-fg hover:opacity-90"
                     >
                       <Play className="w-5 h-5 fill-current" />
                       {inProgress ? t("plex.resume") : t("plex.play")}

frontend/src/components/PlexPlaylistView.tsx

@@ -569,7 +569,7 @@ export default function PlexPlaylistView({
           {items.length > 0 && (
             <button
               onClick={() => onPlay(order[0]!, order)}
-              className="inline-flex items-center gap-2 rounded-xl bg-accent px-4 py-2 font-medium text-white hover:opacity-90"
+              className="inline-flex items-center gap-2 rounded-xl bg-accent px-4 py-2 font-medium text-accent-fg hover:opacity-90"
             >
               <Play className="h-5 w-5 fill-current" />
               {t("plex.playlist.playAll")}

frontend/src/components/UpNextCard.tsx

@@ -86,7 +86,7 @@ export function UpNextCard({
         <div className="mt-auto flex items-center gap-2 pt-2.5">
           <button
             onClick={onAdvance}
-            className="flex items-center gap-1.5 rounded-full bg-accent px-3 py-1.5 text-xs font-semibold text-black hover:brightness-110"
+            className="flex items-center gap-1.5 rounded-full bg-accent px-3 py-1.5 text-xs font-semibold text-accent-fg hover:brightness-110"
           >
             <span className="relative grid h-5.5 w-5.5 flex-none place-items-center">
               <svg viewBox="0 0 24 24" className="absolute inset-0 -rotate-90">

frontend/src/components/plexCards.tsx

@@ -140,7 +140,7 @@ export function PlexPosterCard({
           <div className="absolute inset-0 bg-black/25" />
           <div className="absolute inset-x-0 top-[30%] flex justify-center">
             <div
-              className="grid h-12 w-12 scale-90 place-items-center rounded-full text-white shadow-xl transition-transform duration-200 group-hover:scale-100"
+              className="grid h-12 w-12 scale-90 place-items-center rounded-full text-accent-fg shadow-xl transition-transform duration-200 group-hover:scale-100"
               style={{
                 background:
                   "radial-gradient(circle at 38% 32%, color-mix(in srgb, var(--accent) 72%, white), var(--accent))",

frontend/src/components/plexDetailUi.tsx

@@ -144,7 +144,7 @@ export function PrefToggle({
         className={`relative h-4 w-7 rounded-full transition ${on ? "bg-accent" : "bg-border"}`}
       >
         <span
-          className={`absolute top-0.5 h-3 w-3 rounded-full bg-white transition-all ${on ? "left-3.5" : "left-0.5"}`}
+          className={`absolute top-0.5 h-3 w-3 rounded-full transition-all ${on ? "left-3.5 bg-accent-fg" : "left-0.5 bg-white"}`}
         />
       </span>
     </button>

frontend/src/components/ui/form.tsx

@@ -43,8 +43,8 @@ export function Switch({
       className={`w-9 h-5 rounded-full transition relative shrink-0 disabled:opacity-50 disabled:cursor-not-allowed ${checked ? "bg-accent" : "bg-border"}`}
     >
       <span
-        className={`absolute top-0.5 w-4 h-4 rounded-full bg-white shadow transition-all ${
-          checked ? "left-4.5" : "left-0.5"
+        className={`absolute top-0.5 w-4 h-4 rounded-full shadow transition-all ${
+          checked ? "left-4.5 bg-accent-fg" : "left-0.5 bg-white"
         }`}
       />
     </FocusSafeButton>