CLI: Display non-default ignore file option

We currently have `--respect-gitignore` / `--no-respect-gitignore` flags which toggle automatic exclusion of files listed in a `.gitignore` file and “other standard ignore files”. The CLI help menu displays `--respect-gitignore` but it is already the default behavior. Instead, it should display the negative option to clarify the default behavior.

Start at the CLI option definition and help output for --respect-gitignore and --no-respect-gitignore. Run the CLI help command to confirm the current display, then verify that the negative option is shown while the default ignore behavior remains unchanged.

Written by the indexing model from the issue text.