End a season run for good, so nothing it held can spend later.

A human decision: call only after the user explicitly agrees to end this run, with userConfirmed=true. The run becomes ended, a terminal status: advance, the background retries and the hourly sweep never move it again. Ending releases what was approved and not yet spent (a product run's spendQuote is cleared), cancels every episode's booked-but-unstarted work through its own core and refunds it (a quoted or booked recording, a story job still holding its credits), and names what was already running (a recording being made, an episode writing, a video rendering or finishing): that finishes by itself, its result is the user's, and nothing starts after it. ended.sentence says all of it in one line. A finished (complete) run is refused; ending an ended run answers with it unchanged. It is undone only by starting a new run: the ended run lets go of its durable identity, so creating the season's run again makes a new one. Requires Idempotency-Key.