Wind Down mode: Alternative schedule for color filter

**Describe the enhancement or feature you'd like**
Google digital wellbeing have an option to turn on greyscale filter after sleeping hours.

There would be great to have an alternative schedule to turn on 'use color filter' during only the specified hours, instead of being on for the whole dark mode period.

**Describe alternatives you've considered**

**Additional context**
Add any other context or screenshots about the feature request here.

The issue does not name files, tests, or entry points. Start by locating the existing color-filter setting and the schedule that governs dark mode, then determine how a separate sleeping-hours schedule should interact with them. Done means color filtering activates only during its configured hours without changing the existing dark-mode schedule.

Written by the indexing model from the issue text.