docs: change hero stat from agent count to feature highlight

Replaced '19+ specialized agents' with 'Persistent team memory' in the
trust strip — highlights a user-facing feature instead of internal team size.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: bradygaster

docs/src/pages/index.astro

@@ -154,7 +154,7 @@ const base = import.meta.env.BASE_URL;
       <div class="flex flex-wrap items-center justify-center gap-x-8 gap-y-2 text-lg">
         <div class="flex items-center gap-2 text-surface-600 dark:text-surface-300">
           <span class="w-1.5 h-1.5 rounded-full bg-squad-500"></span>
-          <span>19+ specialized agents</span>
+          <span>Persistent team memory</span>
         </div>
         <div class="flex items-center gap-2 text-surface-600 dark:text-surface-300">
           <span class="w-1.5 h-1.5 rounded-full bg-accent-500"></span>