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- Web UI: grey out stale results while a search runs and cancel superseded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

tests/unit/nzb.spec.ts

@@ -10,7 +10,7 @@ test.group('nzb / buildNzb', () => {
           poster: 'poster@example.invalid',
           date: 1_790_000_000_000,
           groups: ['alt.binaries.test'],
-          segments: { '2': { id: 'b@x', size: 700 }, '1': { id: 'a@x', size: 800 } },
+          segments: [{ number: 2, id: 'b@x', size: 700 }, { number: 1, id: 'a@x', size: 800 }],
         },
       ],
       { title: 'Some.Show.S01E01' }
@@ -53,3 +53,15 @@ test.group('nzb / parseNzb', () => {
     assert.isNull(parseNzb('<html>not an nzb</html>'))
   })
 })
+
+test.group('nzb / stored segment lists', () => {
+  test('pack and unpack round-trip, in order, also with gaps in the numbering', async ({ assert }) => {
+    const { packSegments, unpackSegments } = await import('#lib/nzb/segments')
+    const sequential = Array.from({ length: 300 }, (_, i) => ({ number: i + 1, id: `Ab${i}Cd-1790600369${i}@nyuu`, size: i === 299 ? 1234 : 740000 }))
+    assert.deepEqual(unpackSegments(packSegments([...sequential].reverse())), sequential)
+    const gaps = [{ number: 3, id: 'c@x', size: 3 }, { number: 1, id: 'a@x', size: 1 }, { number: 7, id: 'g@x', size: 7 }]
+    assert.deepEqual(unpackSegments(packSegments(gaps)), [gaps[1], gaps[0], gaps[2]])
+    assert.deepEqual(unpackSegments(packSegments([])), [])
+    assert.isBelow(packSegments(sequential).length / sequential.length, 30)
+  })
+})