The par2 merge: releases whose files one par2 set describes become one

The prober stores, per probed article that starts a file, the MD5 of its
first 16 KiB (file_hashes), and per par2 body the set's whole file list
(par2_files, par2_sets): FileDesc holds the same hash per file, whatever
the file was renamed to. releases:merge (the merger service, no NNTP)
merges every minute the releases of one group, posted within 48 hours of
a release holding the set's par2, whose files the set describes, into the
one with the most files: chunks, probe candidates, inspections, hashes and
counts move; the par2's shared name when none was readable; release_merges
keeps what went where. Obfuscated uploads whose files were each a release
of their own ("[9/20] - "14f5999a…"", hep: 13,232) become one.

Also: corpus_sweep.py counts the marked ranges without psql's command tag.

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

deploy/README.md

@@ -19,6 +19,7 @@ homelab with the deploy key, whose forced command
 | `node-api` | `usenet-rebuild` | the edge workers' API (leases, streams, batches); port 3335 on the compose network only (`HTTP_ROUTES=node`) |
 | `coordinator` | `usenet-rebuild` | prefetching (all NNTP connections), planning, the tail, merging, settling |
 | `prober` | `usenet-rebuild` | phase 2: reads the probe queue's articles over `PROBE_CONNECTIONS` (6) connections, stores what they show |
+| `merger` | `usenet-rebuild` | the par2 merge: releases whose files one par2 set describes become one (no NNTP) |
 | `edge` | `usenet-rebuild-edge` (target `edge`) | the Rust worker, `--threads $EDGE_THREADS` (8) |
 | `edge-ts` | `usenet-rebuild` | the TypeScript worker, profile `edge-ts`, not started |
 | `ace` | `usenet-rebuild` | one-off ace commands, profile `tools` |