Improve admin panel and sale countdown banner

- Remove 'apply to all' option from sale manager - only selected items
- Fix PLA Translucent to be spool-only (no refill option)
- Sale countdown shows actual max percentage from database
- Update banner design: blue-purple-orange gradient instead of red
- Remove fire emoji and promotional text
- Make percentage number larger and yellow for emphasis
- Change 'do' to 'od' in discount text
- Add shimmer animation for subtle effect

app/page.tsx

@@ -175,7 +175,10 @@ export default function Home() {
           </a>
         </div>
         
-        <SaleCountdown />
+        <SaleCountdown 
+          hasActiveSale={filaments.some(f => f.sale_active === true)}
+          maxSalePercentage={Math.max(...filaments.filter(f => f.sale_active).map(f => f.sale_percentage || 0), 0)}
+        />
         
         <FilamentTableV2 
           key={resetKey}