Spotnet import, header backfill, staging and counter grouping, faster search

Spotnet (CONCEPT D29):
- Index free.pt fully and import spots with their descriptions, categories
  and NZBs; a spot renames its release, since Spotnet names are more
  trustworthy than names derived from subjects.
- Find passwords in spot descriptions too, and tell "needs a password we
  have" from "needs a password we don't have".

Content inspection:
- List the contents of 7z (.7z.001) archives, SFV sets, nicovideo uploads
  and other archive-like files; mark yEncBin .bin containers as encrypted.
- Take real names from yEnc headers for randomly named files, and merge
  uploads that were split across posts.

Storage (D31, D32):
- Store segment lists zstd-compressed behind the FileStore accessor.
- group:backfill indexes older headers at low priority and pauses when
  the NVMe or HDD part of the database gets too large.

Grouping (D35, D36):
- Lone header segments wait in staged_segments until a second segment of
  their file arrives, which drops the per-article junk binaries.
- Counter grouping joins random-subject uploads by poster, [i/M] counter,
  part count and day.

Search and maintenance (D33, D34):
- A trigram-indexed search_text column, smaller indexes, estimated stats.
- Passes that clean up nonsense names; weekly index maintenance; GC budgets
  per kind.
- Web UI: grey out stale results while a search runs and cancel superseded
  requests. Count only up to 1,000 matches for the page, which made filter
  clicks take seconds (Newznab keeps the 10,000 cap).

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

start/env.ts

@@ -47,8 +47,18 @@ export default await Env.create(new URL('../', import.meta.url), {
   NNTP_PASSWORD: Env.schema.secret(),
   NNTP_SECURE: Env.schema.boolean(),
   NNTP_POOL_SIZE: Env.schema.number.optional(),
+  NNTP_COMMAND_TIMEOUT_MS: Env.schema.number.optional(),
 
   // Indexer (config/indexer.ts)
+  BACKFILL_MAX_QUEUED: Env.schema.number.optional(),
+  STAGING_GROUPS: Env.schema.string.optional(),
+  COUNTER_GROUPING_GROUPS: Env.schema.string.optional(),
+  FILE_CONCURRENCY: Env.schema.number.optional(),
+  GC_REINDEX_INTERVAL_MS: Env.schema.number.optional(),
+  GC_UNFINGERPRINTED_SECONDS: Env.schema.number.optional(),
+  STAGING_TTL_SECONDS: Env.schema.number.optional(),
+  BACKFILL_MAX_NVME_GB: Env.schema.number.optional(),
+  BACKFILL_MAX_HDD_GB: Env.schema.number.optional(),
   INDEX_INTERVAL_MS: Env.schema.number.optional(),
   INDEX_BATCH_SIZE: Env.schema.number.optional(),
   INDEX_MAX_BATCHES_PER_TICK: Env.schema.number.optional(),
@@ -60,6 +70,7 @@ export default await Env.create(new URL('../', import.meta.url), {
   DEFERRED_EXPAND_MAX_PARTS: Env.schema.number.optional(),
   DEFERRED_CONCURRENCY: Env.schema.number.optional(),
   SPOT_CONCURRENCY: Env.schema.number.optional(),
+  SPOT_IMPORT_DAYS: Env.schema.number.optional(),
 
   // Newznab API (/api): required as ?apikey= when set
   NEWZNAB_API_KEY: Env.schema.secret.optional(),