Fix PDM matrix flakes on PyPI/patch API transport blips (#860)

* Retry PDM backtest cases on transport errors

The PDM matrix runs against production PyPI and the public patch API.
Over the last 7 days 25 pdm-compatibility runs failed on one random
cell each, on unrelated PRs. The version, OS, shape, mode and check
differed every time (rescanIdempotent, appliedExactlyOne,
rescanAfterRelockApplies, ...). Each check judges a CLI scan, install
or rollback. `Run` retries a command once, and only on a non-zero
exit. The CLI usually reports an exhausted patch API fetch in its
JSON while exiting zero, so the cell just fails a later check.

Port backtest-poetry.py's case-level retry (#596). A case is re-run
from a fresh directory, at most three attempts, only when every
failed check recorded transport evidence from the operation it
judged. Evidence is a failed command's request error, PyPI give-up,
patch API 5xx or exhausted 429, or the same in the CLI's JSON error
records. Functional failures are never retried, even when a later
step raises a transport error. Failed attempts' logs go under
attempts/ and are uploaded. A failing case now prints its failed
checks' notes, since the job log alone never said why.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N8YeCUhdg2tKdqyyY7z3sV

* Judge PDM rollback and VEX checks by their run

Bugbot: the final hosted/vendored rollback checks, the unverifiable-
write rollback, the refused-lock VEX and the reverted-lock VEX runs
named no operation, so a transport failure there never made the case
retryable. installedBytesPatched fails together with a blipped pdm
sync and blocked the retry the same way.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N8YeCUhdg2tKdqyyY7z3sV

* Port #851: fix vex alias tests broken on main

Main is red since #605 (4646693): two commands::vex_consumed tests
assume the name-keyed resolver never returns npm-aliased copies, and
#605 taught it to find them. This fails socket-patch-cli --lib in
coverage and test on every PR. Port #851's test-only fix so this PR
can go green; it no-ops once #851 lands.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N8YeCUhdg2tKdqyyY7z3sV

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: mikolalysenko