Smooth live map tracking: travel along the path at the update pace

When a tracked device sends a fix every ~15 s, gliding each marker to its new fix in about a second still reads as choppy (move, wait, move). What flows: keep a queue of waypoints per marker, push each new fix onto it, and set the marker's speed to remaining path length divided by about 1.08x the smoothed interval between fixes (an EMA of arrival gaps). The marker then moves the whole time, through each fix in turn (no corner cutting), and reaches the newest one about when the next arrives. Before the interval is known, use walking pace capped at the sender's spacing, so the first move after a page load doesn't arrive in a moment and stall. With 3+ waypoints queued (a backlog after a gap), catch up in ~2.5 s; snap on huge jumps or under reduced motion. Draw the trail line to the newest fix so the true latest position is never hidden behind the lagging marker, and drive all markers from one requestAnimationFrame loop that stops when every marker arrives. On the data side, poll a cheap positions-only endpoint every 2 s and patch rows in place, but don't stamp the patched rows with the poll's time: a late-delivered fix would look fresh.