Aligns .oxfmtrc.json with the downstream workspace's, which formats this library as packages/levelset when it is vendored there. printWidth was 100, carried over from the Prettier config oxfmt replaced; measured at that width, a `bun run format` in that workspace reflowed 104 of 143 files inside the vendored copy, so the two settings could not both stay. 105 files reflowed, no behavioral change. Kept as its own commit so the reflow never mixes with a real edit — the same reason the earlier printWidth-100 sweep was separated. bun run typecheck clean, bun run lint exits 0, bun run format:check exits 0, bun test 584 pass / 12 skip / 1 fail (pre-existing), generated/block-meta.json unchanged after regeneration.