Fix test warning (#194)

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

src/versions/backfill.rs

@@ -1039,7 +1039,6 @@ mod tests {
             "INSERT INTO clip_failures (library_id, rel_path, content_hash, error, failed_at) VALUES (1, 'v.png', 'v', 'boom', 0)",
         );
         let mut dao = SqliteVersionDao::from_shared(conn.clone());
-        let rows = vec![row("v.png", "v", None)];
         let reviewed = vec![ReviewedLink {
             method: "phash".into(),
             library_id: 1,