Spots: the spotter and the spot inspector, passwords kept apart

Two processes, one NNTP connection each (the coordinator 40 -> 38):
- spots:read (service spotter): free.pt's overviews after the last article
  seen, each spot's full header verified (lib/spotnet from voyager 1, as
  Spotweb), its description, website and NZB articles; the password its
  title or text names; delete/dispose messages applied.
- spots:inspect (service spot-inspector): each spot's compressed NZB read,
  its files listed (spot_files), each matched to the header pass's release
  by the same release identity in one of its groups within 48 h
  (release_spots); unmatched spots matched again hourly, after 24 h a
  release of their own (source spot) with the spot's NZB.
- release_passwords: per release and password, its source (nzb, spot-title,
  spot-text) and spot; the catalog keeps only passworded.
XoverClient.head(); PROBE_CONNECTIONS default 10.

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

start/env.ts

@@ -61,6 +61,11 @@ export default await Env.create(new URL('../', import.meta.url), {
   LEASE_TTL_SECONDS: Env.schema.number.optional(),
   SPOOL_DIR: Env.schema.string.optional(),
   CORPUS_DIR: Env.schema.string.optional(),
+  SPOT_GROUP: Env.schema.string.optional(),
+  SPOT_BACKFILL: Env.schema.number.optional(),
+  SPOT_EVERY_SECONDS: Env.schema.number.optional(),
+  SPOT_MAX_NZB_SEGMENTS: Env.schema.number.optional(),
+  SPOT_STANDALONE_AFTER_HOURS: Env.schema.number.optional(),
   CORPUS_AHEAD: Env.schema.number.optional(),
   PROBE_PIPELINE: Env.schema.number.optional(),
   SPOOL_AHEAD_PER_LEASE: Env.schema.number.optional(),