Prefetch gives remote streams the real window, not a 3.8s cap

Re-verification finding: nextCand applied REMOTE_READY_MS (3.8s) even during a PREFETCH — the next clip starts loading a full 8-bar window early, but the timeout dropped it to local after 3.8s anyway, so a slow-but-reachable archive.org stream could never win, only fail earlier.

▶ Play it: Rail Replacement Rapture — a bed-heavy genre where the found-sound layer carries the room https://stellate.app/?genre=transitwave&seed=7774&path=749.12536,768.12569,730.12569&xdur=13.122

a706118 https://github.com/aboard-io/stellate/commit/a70611865ef06f2ff4ff762ea59375e773ac6c99