Administration is no longer moving wholesale into ihasmail. INBUXA Admin, a
fork of the schema-driven webui (no Enterprise-only code, ordinary fork),
covers the whole server, setup and recovery from its own deployment.
ihasmail keeps its account and tenant administration. Contract additions:
the inbuxa-admin OAuth client, cross-origin access limited to the two
front ends (the server currently allows every origin), and relative OAuth
endpoints on servers with no public URL.