Replace AI copilot icon with elegant two-star design

- Replace complex neuron/atom icon with clean two-star design
- Stars are positioned at different sizes for visual hierarchy
- Design matches existing Redis AI iconography and site aesthetics
- Uses currentColor for consistent theming with button states
- Maintains professional appearance while being more recognizable as AI indicator

This creates a more cohesive visual language with the existing star-based icons used throughout the Redis AI documentation.

Author: mich-elle-luna

layouts/partials/search-modal.html

@@ -24,7 +24,11 @@
         </svg>
       </button>
       <button id="ai-copilot-toggle" type="button" style="height: calc(3rem - 2px);" class="px-3 border border-redis-pen-800 rounded-md bg-white hover:bg-redis-yellow-100 transition-colors flex items-center gap-2" title="Switch to AI Copilot">
-        <span class="text-sm">🤖 AI</span>
+        <svg width="16" height="16" viewBox="0 0 20 20" fill="currentColor">
+          <path d="M6 2.5L7.5 6.5L11.5 7L8.5 9.5L9.5 13.5L6 11.5L2.5 13.5L3.5 9.5L0.5 7L4.5 6.5L6 2.5Z"></path>
+          <path d="M14 6.5L15.5 10.5L19.5 11L16.5 13.5L17.5 17.5L14 15.5L10.5 17.5L11.5 13.5L8.5 11L12.5 10.5L14 6.5Z"></path>
+        </svg>
+        <span class="text-sm">AI</span>
       </button>
       <select id="search-select" style="height: calc(3rem - 2px);" class="w-2/5 pl-3 grow-0 border border-redis-pen-800 rounded-md search-filter bg-white text-left pr-8 appearance-none hidden md:block" autocomplete="off">
         <option value="all" selected>All products</option>