Rebuild: the catalog API and Newznab, from voyager 1

- /api (Newznab: caps, search, tvsearch, movie, music, book, get) for
  Prowlarr, Sonarr and Radarr: voyager 1's controller and XML on the new
  catalog; readable releases not known to miss files; NEWZNAB_API_KEY.
- /api/v1/releases (q, cat, readable, complete, source, poster, size,
  sort, paging), /api/v1/releases/:id with its files (decoded from the
  chunks; NzbService.files, shared with the NZB), /api/v1/stats
  (estimates, plus history and tail progress), /health. Open, as voyager
  1's catalog; the web interface uses it.
- release_category(name): voyager 1's categorizer without the archive
  contents, a generated column with a (category, posted_at) index.
- @adonisjs/static for the web interface (next).

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

start/env.ts

@@ -45,6 +45,9 @@ export default await Env.create(new URL('../', import.meta.url), {
   NNTP_CONNECTIONS: Env.schema.number.optional(),
   NNTP_TIMEOUT_MS: Env.schema.number.optional(),
 
+  // Newznab API key (empty: no key needed)
+  NEWZNAB_API_KEY: Env.schema.secret.optional(),
+
   // Coordinator
   RANGE_ARTICLES: Env.schema.number.optional(),
   TAIL_EVERY_SECONDS: Env.schema.number.optional(),