Fix SHORT_GRASS linkage on Minecraft 1.20.2

[Minecraft0122]

Summary

• use BreweryX's version-aware grass material in default cauldron ingredients and recipes
• use the same compatibility constant while migrating legacy LONG_GRASS data
• avoid linking Material.SHORT_GRASS, which is absent from the supported 1.20.2 API

Verification

• ./gradlew compileJava
• inspected generated bytecode for the affected classes; none reference Material.SHORT_GRASS
• verified against the official Spigot 1.20.2 API artifact that SHORT_GRASS is absent

Closes #201.