fix: use semantic colors across admin pages

src/app/admin/theme/page.tsx

@@ -112,12 +112,12 @@ export default async function AdminTheme({
   return (
     <main>
       <div className="flex items-center gap-3 mb-6">
-        <div className="w-10 h-10 rounded-xl bg-gradient-to-br from-[var(--color-primary)]/20 to-[var(--color-primary)]/5 grid place-items-center">
+        <div className="w-10 h-10 rounded-xl bg-gradient-to-br from-[var(--admin-accent)]/20 to-[var(--admin-accent)]/5 grid place-items-center">
           <span className="text-lg">🎨</span>
         </div>
         <div>
-          <h1 className="m-0 text-xl font-extrabold text-[var(--color-text)]">{t("title")}</h1>
-          <p className="m-0 text-xs text-[var(--color-text-muted)] mt-0.5">
+          <h1 className="m-0 text-xl font-extrabold text-[var(--admin-text)]">{t("title")}</h1>
+          <p className="m-0 text-xs text-[var(--admin-text-muted)] mt-0.5">
             {t.rich("subtitle", { code: (chunks) => <code>{chunks}</code> })}
           </p>
         </div>
@@ -178,7 +178,7 @@ export default async function AdminTheme({
 
         <section className="mt-6">
           <h2 className="admin-section-title">Gradient mix</h2>
-          <p className="text-xs text-[var(--color-text-muted)] mb-2">
+          <p className="text-xs text-[var(--admin-text-muted)] mb-2">
             Control the card header and hero background gradients.
           </p>
           <div className="admin-card">{colorGrid(GRADIENT_FIELDS, current)}</div>
@@ -242,7 +242,7 @@ export default async function AdminTheme({
 
         <section className="mt-6">
           <h2 className="admin-section-title">{t("cssTitle")}</h2>
-          <p className="text-xs text-[var(--color-text-muted)] mb-2">{t("cssSubtitle")}</p>
+          <p className="text-xs text-[var(--admin-text-muted)] mb-2">{t("cssSubtitle")}</p>
           <textarea
             name="custom_css"
             defaultValue={customCss}