`transmission_dispersion_scale` -> `transmission_dispersion` ?

This is very minor, but this name `transmission_dispersion_scale ` seems unnecessarily long.
It functions as the main slider for the dispersion effect, so why not just call it `transmission_dispersion`?

(Then `transmission_dispersion_abbe_number` gives the Abbe control. It could also be abbreviated to `transmission_dispersion_abbe`).

Search the repository for both transmission_dispersion_scale and transmission_dispersion_abbe_number, then inspect the specification and reference implementation locations that define or use them. Confirm the preferred shorter names before changing every relevant occurrence; done means the naming is consistent throughout the project.

Written by the indexing model from the issue text.