Total Size added up each version's data.age and metadata.age, but a
version keeps its value in value.age, so no secret's value was counted.
It now adds up every file in each version directory: the value, the
metadata and the version's two keys, as the plan on the issue decided.
A version directory that cannot be read adds nothing and gets a warning
naming it.
The new tests add a 10000-byte secret and check that the total grows by
at least that much, and check the warning for a version directory that
cannot be read.
Model: opus-5-5
