v0.1.4

Scoping a measured violation to what the pull request actually did.

rules.measurements: off | advisory | block is now in the config schema, and
advisory stays the default: gating is opt-in and never a vendor default. Under
block, a measurement fails a check only when it is both block-eligible, which
is the engine's own precision claim, and answerable to this pull request.

Baselines. Gate records the measurement set it observed at a commit and
compares a pull request against the set stored for its base, so the first run on
a mature repository does not hand back the whole back catalogue. No baseline
never gates, and says so in as many words: "Gate has not looked at the base" is a
different sentence from "the base was clean", and the two never render alike.

Severity bands. A pre-existing violation that this pull request moved into a
worse band can now fail a check, and is reported as already present rather than
as new. Bands are the engine's, ordinal, and coarse enough that re-measurement
noise cannot move one. overflow band regressions are reported and never gate,
because those cuts are shares of a viewport rather than a published standard.

Identity. A markup refactor around an untouched violation carries it over
rather than reading as one fixed plus one introduced, and a violation is placed
against the viewport it was measured at.

Requires a Gate version that knows these keys: an older build rejects them as
unrecognized and skips the review, so pin @v1 or later before writing them.