Blocks system rework:

• blocks.yml now supports weighted entries via optional weight field (defaults to 1). Higher weight = more likely to appear.
• Old blocks.yml is automatically backed up as blocks.yml.bak before migration.

Chest system rework:

• Added vanilla loot table support for natural chest generation. Use chest: <name> in blocks.yml and define <name>: namespace:path in chests.yml.
• Full backward compatibility with legacy item-list chests preserved.

Code improvements:

• Refactored internal codebase, fixed bugs and typos.

Command changes: /ob chest:

• /ob chest <name> set <namespaced_key> — assign a vanilla loot table to a chest alias.
• /ob chest <name> edit — open a GUI to edit the contents of a legacy item-list chest.