[TMC Housekeeping] Deprecate the Aera Vendor Vault & Avantgarde Treasury Vehicle

The Treasury Management RFP has concluded and the Avantgarde COMP strategy ($4.2M) was not selected. This housekeeping proposal deprecates it, together with the near-empty Aera Vendor Vault ($8K), by placing the Vendor Vault's ownership with the TMC's Treasury Timelock and severing Avantgarde's external operator access so the committee can wind both down and redeploy into the selected strategies, within the audited Escrow/Timelock architecture the DAO approved in Prop 580 (2-day delay; the DAO keeps its 60-day t…