DarkUnbug 1.0.6-beta.2 — PvP reflection startup hotfix (EXPERIMENTAL)

FIXES: 1.0.6-beta.1 crashed Fabric 0.20.1 on server startup with
IncompatibleClassChangeError ... FabricLoader.getInstance() must be
InterfaceMethodref. The problem was a wrong FabricLoader CLASS declaration
in the mock compile-time API; actual FabricLoader is an INTERFACE.

The MoreRpgReflectionMixinPlugin has been recompiled against a stub with
the real FabricLoader API interface shape. The class now emits
InterfaceMethodref for FabricLoader.getInstance() / getModContainer().

No changes to the PvP recursion guard Mixin itself. All pre-existing HP
repair, Amethyst/Spell Power, Origins, Cosmetica/Spell Engine code is
byte-for-byte identical to 1.0.5-beta.2.

Still unverified in Minecraft; run on a backup/test server only.
Server must have this mod installed (not merely the clients).
Never install two versions of DarkUnbug concurrently.
