Retrieve a partner's fee position

Returns the fee position of a sourcing partner.

Four different questions about the same money. No single "fees" figure answers any of them:

accruing: earned, not yet on an invoice: a liability that exists but has not been billed. awaiting_approval: billed, not yet approved internally. approved_unpaid: approved and not settled, the nearest thing to what we owe right now. paid_fy: what has actually left this financial year.

A figure moves left to right through those four and is in exactly one at a time, so they never double-count; but they also never sum to anything meaningful, because paid_fy is a flow and the other three are balances. Adding them produces a number with no referent. Render them as four figures, never as a total with parts.

fees_ytd repeats the register's figure so the two cannot disagree, and financial_year_start publishes the boundary both were measured from; India's year runs April to March, and a reader who cannot see the boundary cannot check the number.

The currency is the partner's, taken from their own accruals rather than the book's: a partner may earn in one currency while the lender's book spans several, so the book's currency is not used for a partner's figures. Money is null when the partner's own accruals span more than one.