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>

tests/unit/release/source.spec.ts

@@ -3,7 +3,7 @@ import { SOURCES, sourceCode, sourceName } from '#lib/release/source'
 
 test.group('release source codes', () => {
   test('names and codes map both ways; the codes are fixed', ({ assert }) => {
-    assert.deepEqual(SOURCES, { subject: 1, post: 2, stem: 3, spot: 4, nzb: 5, album: 6 })
+    assert.deepEqual(SOURCES, { 'subject': 1, 'post': 2, 'stem': 3, 'spot': 4, 'nzb': 5, 'album': 6, 'weak-stem': 7 })
     for (const [name, code] of Object.entries(SOURCES)) {
       assert.equal(sourceCode(name), code)
       assert.equal(sourceName(code), name)