feat: interactive TUI with rich/questionary, fakeroot mode, failsafes

- Interactive TUI: distro/init/libc/arch/package selection, ISO config
- Root vs fakeroot mode detection with warnings
- Disk space check before build
- Confirmation prompts with build summary
- Fakeroot support via set_mode() in base.py

pyproject.toml

@@ -7,7 +7,7 @@ name = "euri-mklive"
 version = "0.1.0"
 description = "Universal CLI ISO builder — any distro, from any distro"
 requires-python = ">=3.10"
-dependencies = ["pyyaml>=6", "click>=8"]
+dependencies = ["pyyaml>=6", "click>=8", "rich>=13", "questionary>=2"]
 
 [project.scripts]
 euri-mklive = "euri_mklive.cli:cli"