Fix rustfmt and clippy issues

- Add missing newlines at end of files
- Remove trailing whitespace
- Use next_back() instead of last() for DoubleEndedIterator
- Use &Path instead of &PathBuf for function parameter

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/cli/mod.rs

@@ -50,4 +50,4 @@ pub enum Commands {
 
     /// Show version information
     Version,
-}
+}