voyager 3: the batch store writes releases once, by id references and bytea keys

Each release chunk is a release inserted once: release_key the SHA-1 of
the identity, the owner group and the first article (deterministic; no
numbering under a group lock), identity_key the identity's SHA-1 bytes,
poster_id and group_set_id through catalog_refs (cached per process),
source as a code (weak-stem added), the name into release_texts. A
finished release's candidates are claimable at once; a provisional tail
release is finished by a later chunk of its key, a finished one sent again
is left alone. Gone: joins into earlier releases and across groups, key
numbering, the group lock, the fragment merger. Interim: chunks, counts
and samples keyed by ranges.block_id, a range without a block gets one.

Readers follow: search (posters and group_sets joined, words through
release_texts, posters by id, source by code), the par2 merger, the
sidecar folder, the judge's scraped rule, the spot inspector, the spotter,
the NZB service, releases:regroup, edge:bench. Tests insert fixtures
through tests/functional/helpers/releases.ts; the suites pass again.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

lib/release/source.ts

@@ -15,6 +15,8 @@ export const SOURCES = {
   nzb: 5,
   /** One poster's files that differ only by a number sequence, or share a prefix (voyager 3). */
   album: 6,
+  /** An obfuscated post's stem, read from the yEnc body (identity.ts: weak). */
+  'weak-stem': 7,
 } as const
 
 export type Source = keyof typeof SOURCES