Port to NeoForge 1.21.1

[kaiserproger]

Summary

• switch the root build from ForgeGradle to NeoForge ModDev for Minecraft 1.21.1
• add NeoForge mod metadata and register existing mixins
• port compile-blocking Minecraft/NeoForge API changes across networking, registries, entities, GUI, pathfinding, saved data, and optional compat adapters

Verification

• ./gradlew compileJava processResources
• git diff --check
• mandatory code-simplifier pass
• mandatory code-reviewer pass

Notes

• This is a compiling minimal port-start slice stacked on feature/world-map-route-controls.
• Runtime client/server smoke testing was not run.
• Some optional compat behavior was kept compile-safe where old APIs became private or changed.

[alireza83p]

Did you change it to neo forge 1.21.1?

[dark-neon1101]

so I tried to compile the port to test it out and it crashed with this latest.log
https://mclo.gs/pGPUMFM
you know what i did wrong or where the issue lies?