Uses MermaidJS as default engine

Author: alderg

tools/generate.html

@@ -62,9 +62,9 @@
       <div style="margin-left:auto;opacity:0.5;">
         Engine:
         <select style="padding:2px 6px;border-radius:4px;" title="Engine" id="engine">
-          <option value="gemini">Gemini</option>
-          <option value="chatgpt">ChatGPT</option>
           <option value="mermaidjs">MermaidJS</option>
+          <option value="chatgpt">ChatGPT</option>
+          <option value="gemini">Gemini</option>
         </select>
       </div>
       <div style="opacity:0.5;margin-left:20px;border-radius:4px;">