Fix: restore default appearance when clearing items

[CYFish]

Summary

This PR improves how Fashion Sense restores colors when an appearance is cleared or when a saved color value is missing.

It is related to #61.

Changes

• Reset an appearance's color mask layers to the content pack defaults when using the Hand Mirror clear button or clearing an outfit
• Use the appearance model's default mask color when no saved color key exists, instead of falling back to the player's hair color
• Apply the same default-color fallback to the public API and internal body/shoe color override entries
• Avoid treating internal color override entries as separately drawn shoe/body appearance layers
• Update the local build configuration so the project can be built on macOS without Windows-specific post-build paths

Expected behavior

• Clearing a shirt, pants, sleeves, shoes, hat, or body appearance restores its normal default appearance
• A missing or reset color value no longer causes affected assets to inherit an unrelated color or render black
• Existing content pack default colors remain intact

Scope

This PR does not change Fashion Sense's current shared color-key design. Colors are still stored by appearance type and mask layer, so changing one dyeable shirt or pair of pants can still affect other appearances that use the same color key.

Testing

• Built successfully with dotnet build FashionSense/FashionSense.sln
• Manually verified that clearing clothing restores default colors and that (0, 0, 100) restores the original content-pack colors