fix: syntax errors in all backends, wrong import path, entry point

- fix f-string escape bug in all 5 backends (user password handling)
- fix void.py import: from ..dinit (not .dinit — dinit.py is at package root)
- fix pyproject.toml entry point: cli:cli not cli:main
- add .gitignore for __pycache__

.gitignore

@@ -0,0 +1,5 @@
+__pycache__/
+*.pyc
+*.egg-info/
+dist/
+build/