Release completeness check without reading every binary; SEED_RANGES

release_complete() matched each par2-listed file through a correlated
subquery that scanned all binaries per listed file, run twice per
inserted release_files row: one insert of a few thousand rows ran for
20+ minutes. It now reads the release's files once by release id, and
release_files refreshes once per INSERT statement.

seed:node's SEED_CONNECTIONS/--connections is now SEED_RANGES/--ranges.

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

seed-node/node.env.example

@@ -3,7 +3,7 @@ SEED_URL=https://seed.exp.sforum.nl
 SEED_TOKEN=sn_replace_me
 
 # Ranges seeded at once (about 0.4 CPU core each). 0: no seeding.
-SEED_CONNECTIONS=4
+SEED_RANGES=4
 # Content inspections and archive walks at once (CPU for decoding and parsing; articles come through the seed API).
 SEED_INSPECTORS=0