Slimefun support for 1.21.10

[SI-Abid]

Description

Target the plugin at Minecraft/Paper 1.21.10, bump the project to 5.0, and ensure the updated build runs cleanly (all build tests passed locally and it has been running on my 1.21.10 server, including with the LuckyBlocks addon).

Proposed changes

• Bump project version to 5.0, set Paper properties to 1.21.10, update dough-api to 1.4.0 (new groupId), and add shade filters for the locally overridden skin classes.
• Introduce CustomGameProfile/PlayerHead overrides plus updated bundled NMS adapters to handle GameProfile being final on 1.21.10.
• Default auto-update toggles to false in config.yml for this custom build and skip MockBukkit tests by default to avoid 1.21.10 incompatibilities.
• Refresh the solid block internal tag fixture for 1.21.10 data.

Related Issues (if applicable)

None.

Checklist

• I have fully tested the proposed changes and promise that they will not break everything into chaos.
• I have also tested the proposed changes in combination with various popular addons and can confirm my changes do not break them. (Tested with LuckyBlocks)
• I have made sure that the proposed changes do not break compatibility across the supported Minecraft versions (1.16.* - 1.20.*).
• I followed the existing code standards and didn't mess up the formatting.
• I did my best to add documentation to any public classes or methods I added.
• I have added Nonnull and Nullable annotations to my methods to indicate their behaviour for null values
• I added sufficient Unit Tests to cover my code.

[github-actions]

Pro Tip!
You can help us label your Pull Requests by using the following branch naming convention next time you create a pull request. ❤️

Branch naming convention	Label
feature/**	🎈 Feature
fix/**	✨ Fix
chore/**	🧹 Chores
api/**	🔧 API
performance/**	💡 Performance Optimization
compatibility/**	🤝 Compatibility

---

If your changes do not fall into any of these categories, don't worry. You can just ignore this message in that case! 👀