v0.8.1

Fixed

• The two-round @L example in select --help and in the README could not be run: it reused
  the first round's line numbers (1@L91-120) after a re-diff that renumbers them, so the
  second command failed with exit 2. Both now show the corrected round and say why the numbers
  change; an integration test drives the selectors straight out of the help text.

Changed

• Reading a diff from a terminal — no pipe, no -i — now says so in one line on stderr before
  it blocks. A forgotten pipe used to be indistinguishable from a hang. Nothing is printed when
  stdin is not a terminal, so pipelines are unaffected.
• Selecting by content id resolves through an index built once per invocation instead of a scan
  per id: on a 20 000 sub-hunk diff, selecting every id went from 0.22 s to 0.06 s.
• Release archives are now verified by running the packaged binary and comparing its
  --version with the archive name, so a packaging fault is caught before upload. CI gained a
  cargo semver-checks gate over the public API, the scheduled fuzz run bounds a single input
  with -timeout, and the versions of the tools CI installs are pinned.