The temp directory layout used by the tests was written out four separate
times: once in the documents conftest, once in the paperless checks tests,
once in a fixture local to the NFC upload tests, and once in the helper
behind the old paperless_environment context manager. Each copy covered a
different subset of the settings, so which directories a test actually got
depended on which copy it happened to reach.
The layout now lives in paperless_testing.dirs. build_paperless_dirs owns
where things go and creates them, dirs_settings maps them onto Django
setting names and is pure, and a paperless_dirs fixture in the root conftest
applies that mapping through pytest-django's settings fixture so every app
can reach it. Tests that need a second environment part way through a test
body use the paperless_environment context manager from the same module,
which expresses the identical layout through override_settings. The three
redundant implementations and the old media settings fixture are gone, and
their consumers now take paperless_dirs.