Adds a metadata_complete column (default true for existing rows) to drive
the enrichment queue. New drop-zone uploads always start as false; createDocument
uses an explicit DTO flag or a heuristic (any of date/sender/receivers present →
true); the mass importer applies the same heuristic per row.
New endpoints: GET /api/documents/incomplete-count, /incomplete, /incomplete/next.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
0ce18e1eed