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- Web UI: grey out stale results while a search runs and cancel superseded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>

app/models/file.ts

@@ -1,6 +1,8 @@
 import { DateTime } from 'luxon'
 import { column } from '@adonisjs/lucid/orm'
 import BaseModel from '#models/base_model'
+import { loadedSegments, storedSegments } from '#services/FileStore'
+import type { Segment } from '#lib/nzb/index'
 
 export default class File extends BaseModel {
   @column({ isPrimary: true })
@@ -21,8 +23,12 @@ export default class File extends BaseModel {
   @column()
   declare parts: number
 
-  @column({ columnName: 'message_ids' })
-  declare messageIds: Record<string, any>
+  /** Stored compressed (see FileStore); the model sees the list. */
+  @column({ prepare: (value: Segment[]) => storedSegments(value), consume: (value: Buffer | null) => loadedSegments(value) })
+  declare segments: Segment[]
+
+  @column({ columnName: 'first_message_id' })
+  declare firstMessageId: string | null
 
   @column()
   declare groups: string[]