fix(files): simplify mmd file skeleton to match pptx card pattern

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/preview-panel.tsx

@@ -449,19 +449,19 @@ const MermaidDiagram = memo(function MermaidDiagram({
       return (
         <div className='flex h-full items-center justify-center bg-[var(--surface-1)] p-8'>
           <div
-            className='w-full max-w-[720px] rounded-md bg-[var(--surface-2)] p-8 shadow-medium'
+            className='w-full max-w-[720px] shrink-0 rounded-md bg-[var(--surface-2)] p-8 shadow-medium'
             style={{ aspectRatio: '4 / 3' }}
           >
-            <div className='flex h-full flex-col items-center justify-center gap-5'>
-              <Skeleton className='h-[40px] w-[140px] rounded-md' />
-              <Skeleton className='h-[32px] w-[2px]' />
-              <div className='flex items-center gap-4'>
-                <Skeleton className='h-[40px] w-[110px] rounded-md' />
-                <Skeleton className='h-[2px] w-[32px]' />
-                <Skeleton className='h-[40px] w-[110px] rounded-md' />
+            <div className='flex h-full flex-col justify-between'>
+              <div className='flex flex-col gap-3'>
+                <Skeleton className='h-[18px] w-[45%]' />
+                <Skeleton className='h-[14px] w-[65%]' />
+                <Skeleton className='h-[14px] w-[55%]' />
+              </div>
+              <div className='flex flex-col gap-2'>
+                <Skeleton className='h-[14px] w-[75%]' />
+                <Skeleton className='h-[14px] w-[60%]' />
               </div>
-              <Skeleton className='h-[32px] w-[2px]' />
-              <Skeleton className='h-[40px] w-[140px] rounded-md' />
             </div>
           </div>
         </div>