Rebuild: 2-minute NNTP reply timeout; the Rust worker runs on homelab

Eweka stopped answering on all 40 of the coordinator's long-lived
connections (quiet sockets; a fresh connection fetched the same chunk in
20 s): with a 10-minute timeout the prefetcher fetched one chunk a
minute. The timeout (silence, not duration) is 2 minutes now: 365-411k
articles/s after the restart. tools/probe_chunk.ts times a chunk
compressed and plain.

README and REBUILD.md: edge-node, the Rust worker, is the one running
(8x less CPU per header, 20x less memory than edge:node in production).

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

REBUILD.md

@@ -121,7 +121,9 @@ dropping garbage; 28 TB of compressed overview traffic. Throughput goal:
    cost: a second implementation of lib/headers, lib/release, lib/rules and
    the chunk format, kept identical (check.ts) for as long as both exist.
    Findings, how to run both and how to compare their outputs:
-   `tools/edge-bench-rs/README.md`.
+   `tools/edge-bench-rs/README.md`. Since 2026-10-09 the Rust worker
+   (`edge-node`, same crate) is the one running on homelab: ~8× less CPU
+   per header and 20× less memory than `edge:node` in production.
    Per lease: compressed chunks of 10–50 k lines, in order →
    parse subjects → skip crossposts outside their owner group (of the
    indexed groups in the article's Xref, the one with the lowest priority