fix: balance feature grid to 18 cards (6x3)

Add Remote Plugin Loading card to fill the grid evenly.

Author: ndreno

src/pages/index.astro

@@ -362,6 +362,19 @@ import Layout from '../layouts/Layout.astro';
             Continuous drift detection flags data planes running stale configurations.
           </p>
         </div>
+
+        <div class="card">
+          <div class="w-12 h-12 rounded-lg bg-secondary-subtle flex items-center justify-center mb-4">
+            <svg class="w-6 h-6 text-secondary" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+              <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 16v1a3 3 0 003 3h10a3 3 0 003-3v-1m-4-4l-4 4m0 0l-4-4m4 4V4"></path>
+            </svg>
+          </div>
+          <h3 class="text-xl font-semibold mb-2">Remote Plugin Loading</h3>
+          <p class="text-foreground-muted">
+            Load plugins from HTTPS URLs at compile time with optional SHA-256 integrity verification.
+            Local cache with checksum-based invalidation for fast rebuilds.
+          </p>
+        </div>
       </div>
     </div>
   </section>