feat: add CraftEngine custom block support for island level calculation

[tastybento]

Summary

• Adds CraftEngine block detection to processBlock() alongside ItemsAdder, Oraxen, and Nexo
• Adds isCraftEngine() to Level.java following the same pattern as isItemsAdder() / isNexo()
• Validates CraftEngine block IDs in BlockConfig.isOther() so admins can configure point values in blockconfig.yml
• Bumps bentobox.version to 3.15.0-SNAPSHOT (requires feat: add CraftEngineHook for centralised custom block support BentoBox#2952)

How it works

CraftEngine blocks are identified by their native namespaced ID (e.g. mynamespace:my_block). In blockconfig.yml admins assign values using those IDs directly:

blocks:
  mynamespace:my_block: 50
  mynamespace:custom_ore: 3

CraftEngine can be excluded from level calculation by adding CraftEngine to disabled-plugin-hooks in the Level config.

Context

Requested in issue #418. BentoBoxWorld/BentoBox#2952 adds the CraftEngineHook that this PR uses — no direct CraftEngine compile dependency is needed in Level.

Depends on: BentoBoxWorld/BentoBox#2952

Test plan

• Island with CraftEngine blocks → blocks counted with configured point values
• disabled-plugin-hooks: [CraftEngine] in config → CE blocks ignored (counted as vanilla material)
• Server without CraftEngine → no errors, CE check silently skipped
• Custom CE block IDs accepted in blockconfig.yml; invalid IDs rejected with log warning
• Existing ItemsAdder / Oraxen / Nexo detection unaffected

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