Option to limit the number of authors in results for changes, ownership and ownership-timeline

## Problem being solved
Large repositories often have hundreds of authors that did very small changes, but these get mixed with the regular authors, crowding graphs and outputs.

## Proposal
Create option --authors-limit that accepts the number of authors to include in results (affecting text and graph outputs)

Start by locating the CLI handling and output generation for changes, ownership, and ownership-timeline, including both text and graph outputs. Trace how authors are selected and define completion as a new --authors-limit option that constrains authors consistently across those results.

Written by the indexing model from the issue text.