The v12.0 rebase replaced the PostgreSQL provider's initial migration instead of
adding to it, so an existing database kept the pre-12.0 schema while the code
migrations ran against it and startup aborted on a missing NormalizedUsername.
- restore 20260305010333_InitialPostgreSql as the baseline
- add 20260306000000_UpgradeToServer12Schema carrying it to the 12.0 model
- convert OwnerId and PrimaryVersionId to uuid with explicit casts, clear
unparseable ids and repoint dangling owners at the placeholder item
- drop orphaned permissions and preferences before UserId becomes non-nullable
- add 20260524120336_AddUniqueNormalizedUsernameIndex after the code migration
that fills the column in
- read an empty or unknown encoding.xml EncoderPreset as the default
- cover both paths against a real PostgreSQL and guard the migration ordering
