Current SQLite migration for Snodo.Extensions.Tasks.Store.SQLite.

A fresh install composes every schema step through version two. Existing version-one installations should run Migration.V2 as a separate application-owned migration. The adapter never runs either path itself, so the application retains control of the database file, deployment order, and rollback policy.

SQLite does not support Ecto table prefixes or adding table constraints with ALTER TABLE, so this migration intentionally has no prefix option and creates its complete constraints with the original tables.