Follow the same pattern used for classification: document type now lives
exclusively on DocumentVersion. A migration copies existing values from
documents to their versions. The document filter uses a subquery on the
latest version. All three API surfaces (GraphQL, MCP, CLI), resolvers,
frontend, and e2e tests are updated accordingly.
Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>
9a418a7711