Rebuild: phase 2's prober reads the probe queue

probe:run (compose service prober, PROBE_CONNECTIONS, default 6) claims
waiting candidates of settled releases (lone, then par2, then archive),
fetches each article with BODY over connections of its own (no
compression) and inspects it: the yEnc name and size, the content type
from the first bytes, a par2 set's files, a RAR volume's entries and
whether they're encrypted. Results per release and kind in
release_inspections (CHUNK_TABLESPACE, the HDD); on the release
passworded, inner_name (the largest content name) and inspected_at.
430 = missing, not yEnc = error, both final; connection trouble puts
the candidate back.

Fetch and parse in one process: an article takes ~0.1 s per connection,
parsing a few ms (no queue in between). Parsers from voyager 1 (lib/yenc,
lib/rar, lib/par2, lib/content sniff) with their tests; XoverClient.body;
yencode.

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

deploy/deploy.sh

@@ -45,10 +45,10 @@ docker compose run --rm --no-deps migrate
 # stream keeps the web server from exiting.
 echo "== recreating app services"
 docker compose stop edge
-docker compose up -d --no-deps web coordinator
+docker compose up -d --no-deps web coordinator prober
 docker compose up -d --no-deps edge
 echo "$SHA $(date -Is)" >> "$ROOT/deployed.log"
 # The images this replaced (321 MB each; the root filesystem is the NVMe, with a 10 GB floor).
 docker image prune -f --filter label=com.docker.compose.project=usenet-rebuild >/dev/null
-docker compose ps --format '{{.Service}} {{.Status}}' web coordinator edge
+docker compose ps --format '{{.Service}} {{.Status}}' web coordinator prober edge
 echo "== deployed $SHA"