Image sets: a suffix that ends the number before is a repeat too

"051 - White leather kate054001_1_1.jpg": the index is inside 054001
(set 054, image 001) and _1_1 repeats it, but only a suffix equal to the
whole number before counted as a repeat, so the set kept 054001 and every
image was a release (Duke's threads: 2,791 releases of 3,251 files). A
suffix that the number before ends with is a repeat as well. Both
implementations; tests; fixtures identical.

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

lib/release/identity.ts

@@ -156,7 +156,9 @@ export function imageSet(stem: string): string {
     const previous = /(\d+)\D*$/.exec(before)
     if (!previous) break
     const n = m[1]
-    if (Number(n) === Number(previous[1]) || /^(?:19|20)\d\d$/.test(n) || n.length >= 4) s = before
+    // A repeat: the same number, or the end of the one before ("kate054001_1_1": 054001 ends in 1).
+    const repeat = Number(n) === Number(previous[1]) || previous[1].endsWith(n)
+    if (repeat || /^(?:19|20)\d\d$/.test(n) || n.length >= 4) s = before
     else break
   }
   return /\d/.test(s) ? s.replace(/\d+\D*$/, '') : ''