fix: editable alias in server dialog + Ctrl+Z undo for all input fields

- Alias field no longer disabled when editing server profile
- Duplicate alias check on rename, session pool migration
- Enable undo (Ctrl+Z) on all CTkEntry widgets across the project

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

gui/app.py

@@ -129,7 +129,15 @@ class App(ctk.CTk):
         if server:
             dialog = ServerDialog(self, self.store, server=server)
             self.wait_window(dialog)
-            self.info_tab.refresh()
+            # If alias was changed, re-select the new alias
+            if dialog.result and dialog.result.get("alias") != alias:
+                new_alias = dialog.result["alias"]
+                # Sidebar auto-refreshes via store subscription
+                self.sidebar._select(new_alias)
+                # Migrate session pool reference
+                self.session_pool.rename_server(alias, new_alias)
+            else:
+                self.info_tab.refresh()
 
     def _delete_server(self, alias: str):
         if messagebox.askyesno(t("delete_server"), t("delete_confirm").format(alias=alias)):