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 still adds nothing.
The new test adds a 10000-byte secret and checks that the total grows by
at least that much.
Model: opus-5-5
