test(cli): add comprehensive test coverage for CLI module

Add complete test suite covering all CLI functions:
- Path handling (expand, resolve, glob patterns)
- File collection and validation
- Text reading with charset detection
- File processing with various options
- Output formatting (text and JSON)
- Progress display components
- CLI command interface
- Edge cases and error handling

Achieves 100% test coverage for cli.py module.

Author: titusz