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>

lib/release/identity.ts

@@ -408,10 +408,6 @@ export function releaseIdentity(input: ReleaseInput): ReleaseIdentity | null {
     // set ("Kindly Husband-to-Be.JPG": a thread of 1,177 releases), so the subject alone (LOG.md 2026-10-12 (2)).
     const set = image ? imageSet(stem) : ''
     const parts: (string | number)[] = ['subject', poster, remainder, total ?? set]
-    // An image's set as well under a counter ("Molly Set" [i/50]: "mo103x003.jpg", "mop120x032.jpg": every set of 50 one release):
-    // its name up to its first number, when another follows ("mo103", "destiny-001"; not "IMG_2307", one number an image).
-    const head = image && total !== undefined ? /^(\D*\d+)\D+\d+/.exec(stem) : null
-    if (head) parts.push(head[1])
     // An upload's random stem on its volumes ("[ TOWN ] [ www town ag ] [ TV ] … "Z3mMTMPsoT4ikE_Di3fKnNF21.part01.rar"",
     // "….vol4+4.par2"): under a constant tag every upload of a total was one release (2,338 files for 20; LOG.md
     // 2026-10-14 (51)). No dots or spaces: a scene name ("The.Big.Bang.Theory.S01E01") isn't random.