By: Ben Ruijl <ben@ruijl.ch>
Make zero-color filtering an explicit generation option Replace zero-only numerator grouping with filter_zero_color, disabled by default across Rust, Python, and CLI generation. Show the filtering stage and cumulative zero count in progress updates, and preserve unchecked diagrams when cancelled. Migrate active callers and generated API references. Validate with 140 targeted Rust tests, Python end-to-end tests, the four-loop workload, formatting, and Clippy.