Numbered items: also after a disc code (karaoke)

"Spotlight - 83xx's [16/19] - \"SC8367-12 - Wynette, Tammy - Singing My
Song.zip\"": the disc-and-track code isn't a bare track number, so the
poster-tag rule keyed every track by its own name. A stem starting with
an upper-case code and digits before the track number (SC8367-12,
ZMP050-04) is a numbered item too. Both implementations; tests; fixtures
identical.

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

tests/unit/release/identity.spec.ts

@@ -233,6 +233,9 @@ test.group('release / par2 names', () => {
     const b = id('ai-engineer-complete [422/465] - "006 ai-lesson-4-5-web-search-tools.zip" yEnc', '006 ai-lesson-4-5-web-search-tools.zip')
     assert.equal(a.key, b.key)
     assert.equal(a.name, 'ai engineer complete')
+    // Karaoke discs: a disc code before the track number.
+    const sc = (track: string) => releaseIdentity({ poster: 'p', subject: `Spotlight - 83xx's [16/19] - "${track}.zip" yEnc`, name: `${track}.zip`, weak: false })!
+    assert.equal(sc('SC8367-12 - Wynette, Tammy - Singing My Song').key, sc('SC8367-13 - Jones, George - He Stopped Loving Her Today').key)
   })
 
   test("a poster's constant tag doesn't make one release of all their uploads", ({ assert }) => {