fix(models): Add button, probe of managed models, delete list refresh

- ui.js: mount() now wraps non-node children in text nodes (like h()), so
  mount(el, "") no longer throws in appendChild — this is what broke the
  "Add model" form (applyDefaults cleared a status via mount(x,"")).
- probe_model: resolve managed local models too (they are synthesized into the
  registry, not [[models]]) — probing them no longer returns "model not found".
- models.js: await reload() after delete so the row is removed immediately.

web/js/ui.js

@@ -25,7 +25,9 @@ export function clear(node) {
 
 export function mount(node, ...children) {
   clear(node);
-  for (const c of children.flat()) if (c != null && c !== false) node.appendChild(c);
+  for (const c of children.flat())
+    if (c != null && c !== false)
+      node.appendChild(typeof c === "object" ? c : document.createTextNode(String(c)));
   return node;
 }