* stage-3664: Windows pytest harness hardening (test-only batch #4254/4255/4256/4257/4259)
* test(#3664): Windows pytest-harness compatibility batch
Combines 5 rodboev test-only PRs (#4254/#4255/#4256/#4257/#4259), all under tests/.
Linux assertion paths preserved at full strictness; relaxations + new markers are
Windows/no-fork gated. Codex SAFE + Opus SHIP + changed tests green (cascade-only
full-suite noise is the box artifact). No version stamp (tests-only, Nathan rule).
Co-authored-by: rodboev <rodboev@users.noreply.github.com>
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Co-authored-by: nesquena-hermes <agent@nesquena-hermes>
Co-authored-by: rodboev <rodboev@users.noreply.github.com>