Nightly Build - may be unstable.\n\nCommit: 90aa6a6128e602994a99ef7b0a001250e9b1f7ff\n\nrefactor(economy): remove built-in Vault economy provider

• Delete BuiltInVaultEconomy class and all registration logic
• Remove economyProvider config option and related methods
• Remove ServicePriority import no longer needed
• Simplify economy initialization to rely on external providers only
• Add warning message when economy is enabled but no provider found
• Reduce plugin startup complexity by eliminating custom economy implementation