Add Oraxen furniture mechanic support for island levelling

[tastybento]

Summary

Relates to #390

• Oraxen furniture is entity-based (item displays / armor stands) rather than block-based, so it was completely invisible to the existing chunk block scanner.
• After the block scan completes, a new handleOraxenFurniture() step iterates the entities in every island chunk, identifies Oraxen furniture base entities within the island's protected bounds, and counts each one using the same "oraxen:<id>" namespaced key already used for noteblock/stringblock mechanics.
• Only the base entity of each furniture piece is counted (via OraxenHook.isBaseEntity()) to prevent double-counting multi-entity furniture.
• When Oraxen is not present the new step is a no-op.

Configuration

Furniture values are configured in blockconfig.yml exactly like other Oraxen items:

blocks:
  oraxen:my_chair: 5
  oraxen:my_table: 3

Test plan

• Place Oraxen furniture (furniture mechanic) on an island and run /is level — furniture should contribute to the level.
• Verify noteblock / stringblock mechanics still work as before.
• Verify that when Oraxen is not installed the calculation completes without errors.
• Verify furniture outside the island's protected bounds is not counted.

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud