Batch-generate UUID v4 and v7, with optional hyphens and casing
v4 is fully random; v7 starts with a 48-bit millisecond timestamp so it sorts by time (RFC 9562).
v4 is fully random; v7 embeds a 48-bit millisecond timestamp so it sorts by creation time — a better database primary key that reduces index fragmentation.
v4 carries 122 random bits, so collisions are negligible in practice but not impossible; keep a uniqueness constraint at massive scale.