Add Server-Side Mod & Resource Pack Blacklist Support

Add a built-in client mod and resource pack blacklist system for Paper/Spigot servers.

Server owners could have files such as blacklist-mods.yml and blacklist-resourcepacks.yml where they list prohibited mods or resource packs.

When a player joins, the client would perform a secure check to determine whether any blacklisted item is installed. The server should NOT receive or reveal the player's complete mod/resource pack list. It should only receive a result such as "CLEAR" or "BLACKLIST_DETECTED".

If a blacklisted mod or resource pack is detected, the server can automatically kick the player with a configurable message.

Example:

blacklist-mods.yml:

• ExampleMod

• AnotherMod

blacklist-resourcepacks.yml:

• ExamplePack

This would give server owners a simple built-in way to prevent specific prohibited mods or resource packs while protecting player privacy. It would also reduce the need for third-party plugins and could be useful for PvP, survival, and competitive servers.