refactor: use BentoBox CraftEngineHook instead of direct API calls

[tastybento]

Summary

• CraftEngineCustomBlock now delegates to CraftEngineHook static methods from BentoBox instead of importing CraftEngine classes directly
• Removes the craft-engine-core compile dependency (no longer needed); craft-engine-bukkit is kept for CraftEngineListener
• Bumps bentobox.version to 3.15.0-SNAPSHOT (requires feat: add CraftEngineHook for centralised custom block support BentoBox#2952)

Context

BentoBoxWorld/BentoBox#2952 introduced CraftEngineHook as a centralised hook for CraftEngine, following the same pattern as ItemsAdderHook and OraxenHook. This PR removes the direct CraftEngine API calls from AOneBlock so the addon no longer needs to track CraftEngine's internal API independently of BentoBox.

Depends on: BentoBoxWorld/BentoBox#2952

Test plan

• Phase YAML with CraftEngine block IDs (string form and type: craftengine map form) loads correctly
• Custom CraftEngine blocks spawn on the one-block when the phase is active
• Fallback to STONE occurs if the block ID is invalid
• CraftEngineReloadEvent still triggers AOneBlock phase reload via CraftEngineListener
• All existing tests pass

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