Seed relay: nodes get their headers through the seed API

The seed API keeps a pool of NNTP connections (SEED_NNTP_CONNECTIONS) and
serves GET /api/v1/seed/ranges/:id/chunk?from=&to= for leased ranges:
the gzip stream the news server sent, passed on unopened. seed:node fetches
that way by default (SEED_FETCH=relay), so a node needs only a token and
SEED_CONNECTIONS; SEED_FETCH=direct keeps its own NNTP connections. All
fetching then comes from the indexer's IP (the account allows two).

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

tests/unit/xover_client.spec.ts

@@ -2,6 +2,7 @@ import { test } from '@japa/runner'
 import net from 'node:net'
 import { deflateSync } from 'node:zlib'
 import { XoverClient, parseOverviews } from '#lib/nntp/xover_client'
+import { unzipSync } from 'node:zlib'
 
 const LINES = [
   '101\tShow.S01E01 - "a.mkv" yEnc (1/2)\tposter <p@x>\tMon, 05 Oct 2026 10:00:00 +0000\t<one@test>\t\t700000\t5000\tXref: news.example a.b.test:101',
@@ -86,4 +87,20 @@ test.group('nntp / XoverClient', () => {
       close()
     }
   })
+
+  for (const compress of [false, true]) {
+    test(`hands out overviews as one zlib stream (${compress ? 'as the server sent it' : 'deflated here'})`, async ({ assert }) => {
+      const { port, close } = await server()
+      const client = await XoverClient.connect({ host: '127.0.0.1', port, user: 'u', password: 'p', compress })
+      try {
+        await client.group('a.b.test')
+        const raw = await client.xoverRaw(101, 102)
+        assert.deepEqual(parseOverviews(unzipSync(raw).toString('utf8')).map(([n]) => n), [101, 102])
+        assert.lengthOf(parseOverviews(unzipSync(await client.xoverRaw(1, 1)).toString('utf8')), 0)
+      } finally {
+        client.close()
+        close()
+      }
+    })
+  }
 })