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>

core/server_store.py

@@ -357,7 +357,14 @@ class ServerStore:
         servers = self._data.get("servers", [])
         for i, s in enumerate(servers):
             if s["alias"] == alias:
+                new_alias = updated.get("alias", alias)
                 servers[i] = updated
+                # If alias changed, migrate status
+                if new_alias != alias:
+                    with self._statuses_lock:
+                        old_status = self._statuses.pop(alias, None)
+                        if old_status:
+                            self._statuses[new_alias] = old_status
                 self._save()
                 self._notify()
                 return