Rebuild: the coordinator spools replies without inflating them

On homelab (1 Gbit, 20 connections, ~630k articles/s) the coordinator
used 1.3-1.7 cores, mostly GC of the text it inflated only to know a
compressed reply was complete, plus a copy of every reply. A raw reply
is now complete when it ends in ".\r\n" (no copy): 0.4-0.5 cores at
the same rate.

".\r\n" can also end a network read inside the compressed data (~1 in
16M reads, a few dozen times over the whole target). Such a chunk
doesn't inflate on the worker: it reports it (POST ranges/:id/corrupt),
the spooled chunk is removed and the range goes back to the queue; the
prefetcher fetches it again. The rest of that reply breaks the
connection's next command, so the connection is replaced.

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

app/controllers/node_controller.ts

@@ -74,6 +74,12 @@ export default class NodeController {
     return this.lifecycle(ctx, (rangeId, nodeId) => Leases.finish(rangeId, nodeId))
   }
 
+  /** POST /ranges/:id/corrupt { from }: a chunk that doesn't inflate; the range goes back. */
+  async corrupt(ctx: HttpContext) {
+    const from = Number(ctx.request.input('from'))
+    return this.lifecycle(ctx, (rangeId, nodeId) => Leases.corrupt(rangeId, nodeId, from))
+  }
+
   async release(ctx: HttpContext) {
     return this.lifecycle(ctx, (rangeId, nodeId) => Leases.release(rangeId, nodeId))
   }