Capture's routes (downloads, files, public watch links) and the token list no longer build SQL, call
the session or set a model's fields: reads are downloads/queries, writes the unit's service (service,
folders, links, quota), and each write flushes for the handler to commit. Whose a row is goes
through userscope (owned_by, owned_row), which owned_or_404 now uses too.
The fence holds Capture below its routes as well: it reads only Catalog's and Plex's tables, writes
no other unit's, filters owners through userscope and commits only in its jobs and the upload
ingest. A test per service use case, among them that the tray lists only the caller's files.