STYLED - Roll out the layered card system to the admin workspace

The double-layer AppCard look showcased in the UI Kit was only applied on
the public frontend; every admin surface was pinned to layer=single and
stayed flat. Convert the admin section/container cards to the default
layered look, keeping compact metric tiles, toolbars, image tiles and
nested leaf cards single.

Add AppCard contentClassName so content utilities (space-y-*, grid, flex)
keep applying to the inner shell after the switch to double layer.

components/admin/portfolio-projects-overview.tsx

@@ -85,7 +85,7 @@ export async function PortfolioProjectsOverview({
       <div className="grid gap-4 xl:grid-cols-2">
         {projects.map((project, index) => (
           <MotionFade key={project.id} delay={0.06 + index * 0.03}>
-            <AppCard interactive layer="single" className="h-full">
+            <AppCard interactive className="h-full">
               <CardContent className="flex flex-col gap-4 p-5 lg:flex-row lg:items-center lg:justify-between">
                 <div className="space-y-2">
                   <div className="flex flex-wrap items-center gap-2">
@@ -122,7 +122,7 @@ export async function PortfolioProjectsOverview({
         ))}
 
         {projects.length === 0 ? (
-          <AppCard layer="single" className="xl:col-span-2">
+          <AppCard className="xl:col-span-2">
             <CardContent className="p-6 text-sm text-muted-foreground">
               {copy.empty}
             </CardContent>