Take the image set head back out of the subject key

f1c5af5's set head (an image's name up to its first number) split sets whose
images aren't named alike: "a1.jpg" beside "a1 (2).jpg", and "468_1000.jpg"
whose first number is the image's (1 release became 211 and 161 on the
corpus). The random volume stem stays. Tests keep both sets whole.

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

tests/unit/release/identity.spec.ts

@@ -443,7 +443,7 @@ test.group('release / par2 names', () => {
     assert.notEqual(r('022', '457', "r86_022 - Gwen Guthrie - Ain't Nothing Going on but the Rent.mp3").key, r('022', '333', "r98_333 - Jellie - Roller Coaster.mp3").key)
   })
 
-  test("under a constant tag an upload's random stem, and an image's set, bound the subject", ({ assert }) => {
+  test("under a constant tag an upload's random stem bounds the subject", ({ assert }) => {
     const id = (subject: string, name: string) => releaseIdentity({ poster: 'Kim <Jong-Un@town.ag>', subject, name, weak: false })!
     const town = (i: string, n: string) => id(`[ TOWN ] [ www.town.ag ] [ TV ] [${i}/20] - "${n}" yEnc`, n)
     assert.equal(town('01', 'Z3mMTMPsoT4ikE_Di3fKnNF21.part01.rar').key, town('18', 'Z3mMTMPsoT4ikE_Di3fKnNF21.vol4+4.par2').key)
@@ -452,9 +452,10 @@ test.group('release / par2 names', () => {
     // A scene name keeps the subject's key, so its nfo stays with it.
     const show = (i: string, n: string) => id(`Some.Show.S01E01 [${i}/20] - "${n}" yEnc`, n)
     assert.equal(show('01', 'The.Big.Bang.Theory.S01E01.part01.rar').key, show('20', 'The.Big.Bang.Theory.S01E01.nfo').key)
-    const molly = (i: string, n: string) => id(`Molly Set [${i}/50] - "${n}" yEnc`, n)
-    assert.equal(molly('01', 'mo103x003.jpg').key, molly('02', 'mo103x004.jpg').key)
-    assert.notEqual(molly('01', 'mo103x003.jpg').key, molly('01', 'mop120x032.jpg').key)
+    // An image set under one subject stays one release whatever its images are named ("a1.jpg", "a1 (2).jpg"; "468_1000.jpg").
+    const tender = (i: string, n: string) => id(`Tender TEEN SEX in HD - File ${i} of 435 - ${n}`, n)
+    assert.equal(tender('001', 'a1 (2).jpg').key, tender('002', 'a1.jpg').key)
+    assert.equal(tender('003', 'a2 (2).jpg').key, tender('002', 'a1.jpg').key)
   })
 
   test('an image without words around it is keyed by its set', ({ assert }) => {