fix: patchwork skin correctly develops from fur or scales

[chaosvolt]

Purpose of change

This tackles chimera mutants waffling weirdly between fur and scales by making the patchwork skin mutation actually evolve from either of the relevant mutations.

Fixes #4567

Describe the solution

1. Set both LIGHTFUR and SCALES mutations to have PATCHSKIN1 as a valid changes_to, so either mutation can evolve into it if given the chance.
2. Changed PATCHSKIN1 to have LIGHTFUR and SCALES for prereqs instead of SKIN_ROUGH, which should create a one-way relationship for the mutations.

Describe alternatives you've considered

1. Setting valid to false for Patchwork Skin so that generic mutagen can't risk triggering a potential one-way relationship. This would mean that aspiring chimeras chugging generic mutagen would still witness the eternal fur-vs-scale dance.
2. Simply removing fur and scales from chimera category outright.
3. Bullying the issue OP into PRing this fix themselves like Viss wanted.

Testing

1. Checked affected file for syntax and lint errors.
2. Load-tested and chugged an assload of chimera mutagen.
3. Observed Rough Skin developing into Lightly Furred, then later on into Patchwork Skin instead of committing waffle crimes.

Additional context

Checklist

[chaosvolt]

Been in approval for 3 days so :3