refactor: clean up code and improve variable naming

- Removed unnecessary blank lines in cx_setup.py.
- Reformatted conditional checks in meshchat.py for better readability.
- Updated callback variable names in NomadnetDownloader for clarity.
- Adjusted version string formatting in version.py for consistency.
- Reordered import statements in prepare_frontend_dir.py for better organization.

scripts/prepare_frontend_dir.py

@@ -1,5 +1,5 @@
-from pathlib import Path
 import shutil
+from pathlib import Path
 
 TARGET = Path("meshchatx") / "public"
 
@@ -12,4 +12,3 @@ if TARGET.exists():
     shutil.rmtree(TARGET)
 
 TARGET.mkdir(parents=True, exist_ok=True)
-