fix(alpine): resolve console errors on editor and agent panel

Initialize coverOpen/coverLoading in editorState, render import file info with x-if instead of x-show (null deref), split x-if/x-for on the agent mention menu, guard m.steps.length and use unique keys for the icon picker. Also reduce htmx swap responses to .main-wrapper so shell scripts (agent panel, base inline) are not re-executed on partial navigation.

static/js/app.js

@@ -366,6 +366,22 @@
     window.scrollTo(0, 0);
   }
 
+  // htmx parses the WHOLE response and executes every <script> it contains,
+  // including shell scripts (agent panel, base inline scripts) that live
+  // outside .main-wrapper. Re-running those corrupts Alpine state (x-for
+  // teardown errors). Before the swap, reduce the response to the
+  // .main-wrapper fragment so only page scripts are executed.
+  document.body.addEventListener('htmx:beforeSwap', function(evt) {
+    var d = evt.detail;
+    if (!d || !d.target || !d.target.classList || !d.target.classList.contains('main-wrapper')) return;
+    if (!d.serverResponse || typeof d.serverResponse !== 'string') return;
+    try {
+      var doc = new DOMParser().parseFromString(d.serverResponse, 'text/html');
+      var mw = doc.querySelector('.main-wrapper');
+      if (mw) d.serverResponse = mw.outerHTML;
+    } catch (e) { /* keep original response on parse failure */ }
+  });
+
   document.body.addEventListener('htmx:afterSwap', function(evt) {
     syncAfterSwap(evt.detail && evt.detail.xhr);
   });