MigrationVersion

A migration's version, ordered the way version numbers are ordered rather than the way text is.

1.9 comes before 1.10, which is the whole reason this is a type and not a String. Parts are held as Long, so a version written as a timestamp - 20260827120000, a convention plenty of projects use - counts as a number rather than overflowing into nonsense.

Missing parts are zero, so 1, 1.0 and 1.0.0 are one version, not three. They compare equal, they hash alike, and two migrations carrying them are a duplicate rather than a sequence. text keeps whichever of them was actually written; canonical is the spelling that goes into the history table.