Extract repeated test command setup into helper functions:
- run_init_with_dirs() for tests with separate config/rules directories
- run_init_with_credential() for tests with credential files
This eliminates code duplication and makes tests more maintainable.
Also fixed duplicate #[test] attribute warning.
- Add test_init_with_separate_rules_directory to verify rules created in custom location
- Add test_init_rules_dir_dry_run to verify dry-run behavior with --rules-dir
- Verify config file contains correct rules path when using separate directory
- All 12 init integration tests passing (11 run, 1 ignored)
- Change &PathBuf to &Path parameter in plan_credential_file_operation
- Use inline format string in log message
- Both formatting and linting now clean
- Add create_mock_credential_file() helper to eliminate duplication
- Replace identical credential JSON creation in two integration tests
- Improves test maintainability and reduces code duplication
- All tests continue to pass with same behavior
