Create: Nomad

Fixed Nomad startup crashes and loading-screen hang.

Changes:

• Fixed dedicated server crash caused by Harpoon Gun loading client-only HumanoidModel code on the server.
• Fixed client getting stuck on the Mojang loading screen from HarpoonGunItem.ARM_POSE missing during enum extension loading.
• Moved Harpoon Gun client arm-pose/render logic into a client-only helper while keeping a safe bridge for NeoForge enum extensions.
• Fixed menu/network code that could touch Minecraft.getInstance() from common code paths.
• Fixed brass backpack loot tables so they reference the registered backpack item IDs instead of missing block IDs.