Further mutant scales refinements

[anoobindisguise]

Summary

Balance "one more stage of Scales mutations, adjust coverage, thresholdify sleek scales"

Purpose of change

I was discussing the matter with @Venera3 and it was noted that Scales mutations could use some more work.

Describe the solution

Sparse Scales has become a lower-tier "entry level" scales that is a requirement for "regular" Scales, which have more full coverage now. Sleek Scales is post thresh Fish only, similar to how Thick Scales is post thresh Lizard only.
In addition, I changed the Bone/Chitin dual layers to a single layer of "Mutant Scales" which is defensively in between bone and chitin.

Describe alternatives you've considered

Do two layers of mutant scales with less thickness and coverage.
Do different coverage and values.

Testing

Loaded up in game and they seem to be working OK. The mutations chain through rough skin->sparse scales->scales->sleek/thick scales.

Additional context

[github-actions]

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• Your skin has grown thick and leathery and a set of heavy green scales has grown to cover most of your body, acting as natural armor. Further, bony scutes cover your extremities, offering additional protection there. While difficult to penetrate, it also limits your flexibility. Greatly reduces wet effects.

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[bombasticSlacks]

Got a materials conflict now 😢