Rebuild: edge:node --max-mbit caps a node's download

For workers on a shared line (poweredge-kantoor: 160 Mbit/s): the range
stream is read at most at the cap, TCP holds the coordinator back. The
cap is the node's, split over its processes (also EDGE_MAX_MBIT).
REBUILD.md: where workers run (connections set the speed; remote workers
take CPU off homelab).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lib/edge/index.ts

@@ -4,3 +4,4 @@ export { toWire, fromWire, type WireBatch } from './wire.js'
 export type { Lease } from './lease.js'
 export { mergeFragments } from './merge.js'
 export type { EdgeSegment, FileMeta } from './scan.js'
+export { throttle } from './throttle.js'