feat(db): add initial migration creating users, profiles, preferences

Generated by `prisma migrate dev --name init` against the local Postgres.
Creates the 6 enums and the 3 tables with their unique indexes and
foreign keys (profiles.user_id and preferences.user_id with ON DELETE CASCADE).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/db/prisma/migrations/migration_lock.toml

@@ -0,0 +1,3 @@
+# Please do not edit this file manually
+# It should be added in your version-control system (i.e. Git)
+provider = "postgresql"