kde: improve maintenance

[trueNAHO]

About

This is a tracking issue for minor kde source code improvements.

This tracking issue should simplify the incoming merge conflict resolution.

Steps

• [ ] https://github.com/danth/stylix/issues/315
• [x] https://github.com/danth/stylix/pull/303
• [x] https://github.com/danth/stylix/pull/314
• [x] https://github.com/danth/stylix/pull/304
• [x] https://github.com/danth/stylix/pull/305
• [x] https://github.com/danth/stylix/pull/316

Unresolved Questions

• [x] Should we rollup the individual PRs?
  • For simplicity, we do not.

[danth]

Feel free to go ahead and merge the approved PRs in the correct order.

A rollup would clean up the commit history a little, but I wouldn't say it's strictly necessary.