Complete archive listings by walking RAR headers, at low priority

Inspection lists only the entries whose headers are in the first segment
of a first volume. A walk hops from header to header, fetching one segment
per entry and volume, in its own queue (one job per collection worker) on
NNTP connections inspection isn't waiting for. content:walk-archives queues
releases inspected earlier (CONCEPT D40).

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

app/services/SevenZipService.ts

@@ -120,6 +120,7 @@ class SevenZipService {
       solid: false,
       headersEncrypted,
       truncated: false,
+      next: 0,
       entries: entries.map((e) => ({
         name: e.name,
         size: e.size,