fix: resolve command script under dashboard subpath (#60)

frontend/index.html

@@ -160,7 +160,7 @@ textarea { resize: vertical; min-height: 120px; }
 <div class="footer">Creative AI-imbued UI • stackchain-dashboard</div>
 
 <script src="/static/markdown.js"></script>
-<script src="/static/commands.js"></script>
+<script src="static/commands.js"></script>
 <script>
 (function(){
   const qs = (s, el=document) => el.querySelector(s);