Revert "ads: restore Magewell 300x250 banner with placeholder SVG creative"

This reverts commit bd19ef8b7f.

src/lib/ads.ts

@@ -30,10 +30,9 @@ export const ADS_728X90: Ad[] = [
  * stacks them vertically and shuffles the order per page-view so each banner
  * cycles through positions. Add new entries here to grow the stack.
  *
- * AJA, Zixi, Lectrosonics, Opengear, Studio Hero were removed pending real
- * creatives (their Adsanity campaigns relied on ads.broadcastbeat.com,
- * which is down). Magewell now has an SVG placeholder pending a real
- * creative. See PENDING_ads.md.
+ * AJA, Zixi, Lectrosonics, Opengear, Studio Hero, Magewell were removed
+ * pending real creatives (their Adsanity campaigns relied on
+ * ads.broadcastbeat.com, which is down). See PENDING_ads.md.
  */
 export const ADS_300X250: Ad[] = [
   {
@@ -43,13 +42,6 @@ export const ADS_300X250: Ad[] = [
     alt: "Telycam Mix One ExploreXE NAB 2026",
     click_url: "https://telycam.com/",
   },
-  {
-    label: "Magewell",
-    size: "300x250",
-    src: "/legacy/ads/magewell-300x250.svg",
-    alt: "Magewell — professional video I/O",
-    click_url: "https://www.magewell.com/",
-  },
   {
     label: "LiveU",
     size: "300x250",