ads: restore Magewell 300x250 banner with placeholder SVG creative

Magewell was removed when Adsanity went away; PENDING_ads.md flagged it
along with AJA/Zixi/Lectrosonics/Opengear/Studio Hero for real creatives.
This restores Magewell with an in-house SVG placeholder (red/dark Magewell
brand color, wordmark + tagline + CTA chip) so the sidebar 300x250 stack
gets three rotating entries again instead of two. Real Magewell creative
to land when sourced from the vendor.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

public/legacy/ads/magewell-300x250.svg

@@ -0,0 +1,28 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 300 250" role="img" aria-label="Magewell">
+  <defs>
+    <linearGradient id="mw-bg" x1="0" y1="0" x2="1" y2="1">
+      <stop offset="0" stop-color="#0a0a0a"/>
+      <stop offset="1" stop-color="#1a1a1a"/>
+    </linearGradient>
+    <linearGradient id="mw-accent" x1="0" y1="0" x2="1" y2="0">
+      <stop offset="0" stop-color="#dc2626"/>
+      <stop offset="1" stop-color="#991b1b"/>
+    </linearGradient>
+  </defs>
+  <rect width="300" height="250" fill="url(#mw-bg)"/>
+  <rect x="0" y="0" width="300" height="4" fill="url(#mw-accent)"/>
+  <rect x="0" y="246" width="300" height="4" fill="url(#mw-accent)"/>
+
+  <!-- wordmark -->
+  <text x="150" y="115" text-anchor="middle" font-family="Helvetica, Arial, sans-serif" font-size="40" font-weight="800" fill="#ffffff" letter-spacing="-1">Magewell</text>
+
+  <!-- tagline -->
+  <text x="150" y="148" text-anchor="middle" font-family="Helvetica, Arial, sans-serif" font-size="13" font-weight="500" fill="#dc2626" letter-spacing="2">PROFESSIONAL VIDEO I/O</text>
+
+  <!-- body -->
+  <text x="150" y="186" text-anchor="middle" font-family="Helvetica, Arial, sans-serif" font-size="12" fill="#9ca3af">Capture · Convert · Stream</text>
+
+  <!-- CTA chip -->
+  <rect x="100" y="200" width="100" height="28" rx="4" fill="#dc2626"/>
+  <text x="150" y="219" text-anchor="middle" font-family="Helvetica, Arial, sans-serif" font-size="12" font-weight="700" fill="#ffffff" letter-spacing="2">EXPLORE →</text>
+</svg>

src/lib/ads.ts

@@ -30,9 +30,10 @@ 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, Magewell were removed
+ * AJA, Zixi, Lectrosonics, Opengear, Studio Hero were removed pending real
- * pending real creatives (their Adsanity campaigns relied on
+ * creatives (their Adsanity campaigns relied on ads.broadcastbeat.com,
- * ads.broadcastbeat.com, which is down). See PENDING_ads.md.
+ * which is down). Magewell now has an SVG placeholder pending a real
+ * creative. See PENDING_ads.md.
  */
 export const ADS_300X250: Ad[] = [
   {
@@ -42,6 +43,13 @@ 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",