Make Ancient Cake Vault audit cross-platform

[SkyBlade1978]

Summary

• make the fixed-world Ancient Cake Vault audit select the nearest saved native Stronghold whose start is actually in CakeWorld's supported Vault biome tag
• validate both the CakeWorld configured-structure tag and vanilla Eye-of-Ender locate route from that selected start
• keep the production palette implementation identical to upstream master

Why

Minecraft's fixed-seed concentric-ring biome search selected different nearest Stronghold starts on Windows and hosted Linux. The hosted start was valid but outside the four CakeWorld biomes currently eligible for Ancient Cake Vault conversion, so the production palette correctly left it vanilla. Earlier PR runs 33685951597, 33689597298, and 33691965645 therefore failed because the fixture treated the nearest native Stronghold as eligible without checking its biome.

Verification

• exact commit: db06b24
• local fresh fixed-seed world: 274/274 GameTests passed
• local same-save reload: 274/274 GameTests passed
• hosted Linux run 33695117948: build/package audit passed and 274/274 GameTests passed
• hosted Linux selected a distinct eligible 176-piece Cookie Forest Vault at 1080,32,-1992 and retained the full edible palette, loot, portal, and Eye-of-Ender contracts
• CodeQL run 33695117914 and wrapper validation run 33695117893 passed
• two local release builds produced byte-identical runtime, sources, and Javadocs jars
• production AncientCakeVaultPalette.java matches upstream master exactly
• OreSpawn and its published 4.0.16.118021 dependency are unchanged