Get the loan pipeline

The whole board in one call: every board-visible stage as a column, the
loans in it, and the column's count and volume.

The counts come from the server, and they are the same numbers the
reports use. Do not recompute them from the returned loans — the board
paginates within a column, so a client-side length would disagree with
the header the moment a team got busy.

Scoping. A loan-officer-scoped token sees that officer's book. A
team-scoped token sees everything. loanOfficerIds narrows within what
you can already see; it never widens it, so passing another officer's id
returns nothing rather than their pipeline.