Fix missing SxExpr wraps in events + pretty-print sx in dev mode + multi-expr render

- Wrap 15 call sites in events/sx_components.py where sx-generating
  functions were passed as plain strings to sx_call(), causing raw
  s-expression source to leak into the rendered page.

- Add dev-mode pretty-printing (RELOAD=true) for sx responses and
  full page sx source — indented output in Network tab and View Source.

- Fix Sx.render to handle multiple top-level expressions by falling
  back to parseAll and returning a DocumentFragment.

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

shared/static/scripts/sx.js

@@ -1262,9 +1262,23 @@
 
     // DOM Renderer
     render: function (exprOrText, extraEnv) {
-      var expr = typeof exprOrText === "string" ? parse(exprOrText) : exprOrText;
       var env = extraEnv ? merge({}, _componentEnv, extraEnv) : _componentEnv;
-      return renderDOM(expr, env);
+      if (typeof exprOrText === "string") {
+        // Try single expression first; fall back to multi-expression fragment
+        try {
+          return renderDOM(parse(exprOrText), env);
+        } catch (e) {
+          var exprs = parseAll(exprOrText);
+          if (exprs.length === 0) throw e;
+          var frag = document.createDocumentFragment();
+          for (var i = 0; i < exprs.length; i++) {
+            var node = renderDOM(exprs[i], env);
+            if (node) frag.appendChild(node);
+          }
+          return frag;
+        }
+      }
+      return renderDOM(exprOrText, env);
     },
 
     // String Renderer (matches Python html.render output)