Extract season overview/workflow cards and add sponsor seed data

Splits AdminSeasonsView into AdminSeasonOverviewCard and AdminSeasonWorkflowCard
for cleaner separation of concerns. Adds SeedSponsorsBootstrapper with demo
sponsor SVG assets and extends SeedCatalog with sponsor seed entries.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/public/demo/sponsors/nekopixel-energy.svg

@@ -0,0 +1,17 @@
+<svg width="512" height="512" viewBox="0 0 512 512" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <rect width="512" height="512" rx="124" fill="url(#bg)"/>
+  <path d="M150 150L214 110L232 188L150 150Z" fill="#FFF1F5"/>
+  <path d="M362 150L298 110L280 188L362 150Z" fill="#FFF1F5"/>
+  <rect x="132" y="170" width="248" height="188" rx="94" fill="#FFF1F5"/>
+  <circle cx="220" cy="244" r="22" fill="#EC4899"/>
+  <circle cx="292" cy="244" r="22" fill="#EC4899"/>
+  <path d="M204 304C224.333 324 250.333 334 282 334C306.667 334 327 324 343 304" stroke="#EC4899" stroke-width="22" stroke-linecap="round"/>
+  <path d="M214 150H298" stroke="#FDE047" stroke-width="18" stroke-linecap="round"/>
+  <defs>
+    <linearGradient id="bg" x1="66" y1="54" x2="436" y2="452" gradientUnits="userSpaceOnUse">
+      <stop stop-color="#0F172A"/>
+      <stop offset="0.52" stop-color="#1D4ED8"/>
+      <stop offset="1" stop-color="#22D3EE"/>
+    </linearGradient>
+  </defs>
+</svg>