Fix _aser_component: evaluate kwargs with _aser not async_eval

_aser_component expands component bodies in SX wire format mode,
but was evaluating kwarg values with async_eval (HTML mode). This
caused SxExpr kwargs to be fully rendered to HTML strings, which
then broke when serialized back to SX — producing bare symbols
like 'div' that the client couldn't resolve.

Fix: use _aser() for kwarg evaluation to keep values in SX format.

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

shared/sx/async_eval.py

@@ -1102,7 +1102,7 @@ async def _aser_component(
     while i < len(args):
         arg = args[i]
         if isinstance(arg, Keyword) and i + 1 < len(args):
-            kwargs[arg.name] = await async_eval(args[i + 1], env, ctx)
+            kwargs[arg.name] = await _aser(args[i + 1], env, ctx)
             i += 2
         else:
             children.append(arg)