Port SchematicPreview to Minecraft 26.2

[mmkk20158]

Summary

• Port SchematicPreview to Minecraft 26.2 on top of upstream's 26.1.2 update.
• Rebuild the preview renderer for 26.2's reverse-Z depth and SubmitNodeStorage / FeatureRenderDispatcher pipeline (MultiBufferSource removed).
• Fix preview depth occlusion with vanilla Projection reverse-Z setup and depth clear 0.0.
• Use a dedicated UI lightmap, full-bright mesh light coords, and preview-only face culling that ignores Litematica in-world render-layer settings.
• Bump Fabric Loader/Loom/API, Gradle wrapper, MaLiLib, Litematica, and Mod Menu to 26.2-compatible versions.

Test plan

• Load schematic browser with MaLiLib + Litematica + Fabric API on Minecraft 26.2
• Confirm list/tile previews render (not black)
• Confirm solids occlude correctly while rotating (no see-through / front-face dropout)
• Toggle fullscreen and freecam preview controls
• Open config menu hotkey and Mod Menu entry if present

[Barkells]

Litematica version 0.28.5 has broken this, if you try to load a schematic it crashes the game.

[N1zyx3]

https://github.com/sakura-ryoko/litematica/releases#release-26.1.2-0.27.11
The changes don’t seem all that complicated, but I’m not very experienced in mod development. I’m sure this is a fix for loading Sponge / Vanilla Structure NBT.