Rebuild: chunk deadline 90 s

At 180 s, 60 chunks were given up in 15 minutes: each held a connection
3 minutes, ~30% of the 40 connections' time, while finished chunks
took 24 s on average (Eweka slow this afternoon).

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

config/coordinator.ts

@@ -42,9 +42,11 @@ export default {
    * closed) and fetched again: a reply that trickles never goes quiet long
    * enough for nntpTimeoutMs, and kept a worker waiting on one chunk for an
    * hour (LOG.md 2026-10-10 (2)). Chunks take 3–35 s; at 300 s, 258 were
-   * given up in 3 hours (~1.4 a minute, each holding a connection 5 minutes).
+   * given up in 3 hours (~1.4 a minute, each holding a connection 5 minutes);
+   * at 180 s 60 in 15 minutes, ~30% of 40 connections' time, while finished
+   * chunks took 24 s on average.
    */
-  nntpChunkDeadlineMs: env.get('NNTP_CHUNK_DEADLINE_SECONDS', 3 * 60) * 1000,
+  nntpChunkDeadlineMs: env.get('NNTP_CHUNK_DEADLINE_SECONDS', 90) * 1000,
   /**
    * A chunk not fetched after this long is asked again on another
    * connection; the first answer wins and the other connection is closed.