fix: news feature security, accessibility, performance improvements

- DOMPurify strict allowlist with sandbox on iframes
- safeColor() CSS injection prevention for category_color
- URL validation (http/https) for images and links
- encodeURIComponent for slug in API calls
- Keyboard navigation on news cards (Enter/Space)
- aria-label, aria-pressed, type=button on all buttons
- 44px touch targets on remaining buttons
- memo() wrappers + stable callbacks (fewer re-renders)
- Canvas draw call batching (~75% reduction)
- TipTap extensions useMemo deps fix ([t] -> [])
- Featured image loading=eager fetchPriority=high (LCP)
- Unsafe Number(id) NaN guard

src/components/admin/Toggle.tsx

@@ -1,27 +1,45 @@
+import { cn } from '../../lib/utils';
+
 interface ToggleProps {
   checked: boolean;
   onChange: () => void;
   disabled?: boolean;
+  'aria-label'?: string;
+  className?: string;
 }
 
-export function Toggle({ checked, onChange, disabled }: ToggleProps) {
+export function Toggle({
+  checked,
+  onChange,
+  disabled,
+  'aria-label': ariaLabel,
+  className,
+}: ToggleProps) {
   return (
     <button
+      type="button"
       role="switch"
       aria-checked={checked}
+      aria-label={ariaLabel}
       onClick={onChange}
       disabled={disabled}
-      className={`flex min-h-[44px] items-center ${disabled ? 'cursor-not-allowed opacity-50' : 'cursor-pointer'}`}
+      className={cn(
+        'flex min-h-[44px] items-center',
+        disabled ? 'cursor-not-allowed opacity-50' : 'cursor-pointer',
+        className,
+      )}
     >
       <div
-        className={`relative h-8 w-14 rounded-full transition-colors ${
-          checked ? 'bg-accent-500' : 'bg-dark-600'
-        }`}
+        className={cn(
+          'relative h-8 w-14 rounded-full transition-colors',
+          checked ? 'bg-accent-500' : 'bg-dark-600',
+        )}
       >
         <div
-          className={`absolute left-1 top-1 h-6 w-6 rounded-full bg-white transition-transform duration-200 ${
-            checked ? 'translate-x-6' : 'translate-x-0'
-          }`}
+          className={cn(
+            'absolute left-1 top-1 h-6 w-6 rounded-full bg-white transition-transform duration-200',
+            checked ? 'translate-x-6' : 'translate-x-0',
+          )}
         />
       </div>
     </button>