v0.15.0

• Added stdin: to Backspin.run and Backspin.compare to pipe a String into the command, replacing sh -c wrappers. For compare, give a side as {command:, stdin:}. Stdin is saved on every snapshot like stdout and stderr (empty when not given), so re-recorded files gain a stdin line, but it is not compared.
• Changed Backspin.compare to skip credential scrubbing, so filters, matchers, and diffs see raw output and scrubbing can no longer hide mismatches (generic patterns could turn different paths into identical star runs). run and capture still scrub.
• Added env: to Backspin.compare side Hashes ({command:, env:, stdin:}), so each command can get its own environment. A side's env replaces the top-level env: for that side, and each snapshot records the env it ran with.