No behavior change.
Round 7 removed the loose-mode `console.warn` from selection — it was
encryption-blind and duplicated the caveat printed moments later. This test
kept asserting `warn` was called with "0644" and kept passing, because the
caveat also contains the mode. So it was green while describing a code path
that no longer exists: named "warns once at selection", commented as if the
selection warning were the thing under test, and pinned to a substring loose
enough that either line would satisfy it.
Asserts the caveat's full sentence now, so it is fastened to the surviving
mechanism rather than to whichever line happens to mention the mode.
Also records what it took to reach this state at all, since it is not
obvious and I had it wrong: as the file's owner you *cannot* stage a
loose-mode descriptor, because `tightenSecretFilePermissions` repairs a 0644
file to 0600 during selection and the report is then correctly "owner-only".
It is only real for a file owned by another user or on a read-only mount,
which is why the chmod is mocked — standing in for a privilege a test cannot
drop.
Found by @mcp-inspector-v2-f1, who tried to screenshot the state for the PR
body and got "Owner-only permissions." instead.
Signed-off-by: cliffhall <cliff@futurescale.com>