fix: ctxMenuDelete triggers sidebar refresh via flowdeck:sidebar-refresh

deleteWithUndo() (called by ctxMenuDelete) was removing the node from the
local tree but never notifying the sidebar to refresh. Added dispatch of
'flowdeck:sidebar-refresh' event so the sidebar tree updates dynamically
without requiring a full page reload.

app/templates/local_workspace.html

@@ -1224,6 +1224,8 @@ window._wsInitData = (function() {
         self.undoVisible = false;
         self.undoItemId = null;
       }, 5000);
+      // Notify sidebar to refresh its tree
+      document.dispatchEvent(new CustomEvent('flowdeck:sidebar-refresh'));
     },
     undoDelete() {
       if (this.undoTimeout) clearTimeout(this.undoTimeout);