Excavate

fix(excavate): integrate KwahsCore, fix crop duplication, add config screen

• Add KwahsCore build integration (srcDir, mavenLocal)
• Fix auto-replant item duplication: consume a seed from drops before replanting
• Cancel BreakEvent for crops so origin block is also replanted
• Switch to SafeConfig wrappers and add first-tick config validation
• Add config screen with auto-replant toggle, enabled by default
• Fix mc.level null dereference in highlight renderer
• Fix clickedFace thread safety (skip client-side writes)
• Remove misleading variable aliases and fix level/radius shadowing