Follow-up to the salvaged per-package pin isolation (#125400). Once a
failing pin no longer aborts the run, the surviving pins still run the
venv sync, whose receipt finalizes `ok` as latest.json. `hermes pm
status` and the desktop sync card read latest.json, so a run that left a
package on its old pin and exited 1 was recorded as a clean success.
Write a kind=update `failed` receipt after the sync, with one failed step
per pin, whenever any pin failed (also when every pin failed, which
previously wrote no receipt at all). Trim the tests to the two
invariants and assert the receipt in the mixed case.
de06a61c51