Record the phase 5 ScoreSaber merge and map OST hashes in the sync

ScoreSaber names official levels "ost_<LevelId>" where BeatLeader uses
"<levelid>"; ssMapHash applies that for leaderboard snapshots and maps.
The plan records the merge results and where it differs from the steps.

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

scripts/archive/scoresaber.ts

@@ -102,6 +102,14 @@ function seedFromScraper(playerId: string, items: SSItem[]): void {
 	if (copied) console.log(`  copied ${copied} replays from ${dir}`);
 }
 
+/**
+ * The map hash BeatLeader and the archive use for a ScoreSaber item: lowercase, and for official
+ * levels the level id without ScoreSaber's "ost_" prefix (BeatLeader: "beatsaber", SS: "ost_BeatSaber").
+ */
+export function ssMapHash(it: SSItem): string {
+	return it.leaderboard.songHash.toLowerCase().replace(/^ost_/, '');
+}
+
 export function ssHashes(playerId: string, sinceUnix = 0): string[] {
-	return [...new Set(archivedSSScores(playerId, sinceUnix).map((it) => it.leaderboard.songHash.toLowerCase()))].sort();
+	return [...new Set(archivedSSScores(playerId, sinceUnix).map(ssMapHash))].sort();
 }