Fix Undefined symbol: div — delegate HTML tags to renderDOM in sxEval

When an HTML tag like (div) appears as a kwarg value in SX wire format,
callComponent evaluates it with sxEval (data mode) which doesn't handle
HTML tags. Now sxEval delegates to renderDOM for any render expression
(HTML tags, SVG tags, fragments, raw!, components).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/static/scripts/sx.js

@@ -457,6 +457,9 @@
           return new _Thunk(expanded, env);
         }
       }
+
+      // HTML tag or component in data position — delegate to renderDOM
+      if (_isRenderExpr(expr)) return renderDOM(expr, env);
     }
 
     // Function call