Business resources hub — capability areas :: Business Bootstrap

Summary

Reframed the component as a support-systems hub with capability areas: Email, Scheduling, Design, Vault, Org infra (landing pages + nav sections).
Added explanation articles under area trees:
Promoted Stack map (was flat "business resources" catalog) and extended Defaults by org stage.
Kept published email page paths stable (explanation/…, how-to/…, tutorials/…); new topics live under area folders so how-tos and interconnect pages can grow without a second Antora component.