Ship the race batch mode as one patch release.

The feature: `peaks batch diagnose` (one item is not a batch, so the
single-task lane is untouched), a unified acceptance gate that runs the
single-task gate verbatim once for the whole batch and can attribute a red
gate to one item or to the integration between them, a fix phase whose
scoped test runs before the status flip, and context monitoring that lands
the diagnostic report on disk, treats a phase boundary as the best
compaction point rather than a reason to defer, and states facts without
ever handing the compaction step to the user.

It also lands the A-1 acceptance the probe left open. Probe A concluded
the fast-lane allow path, but only tested identity resolution, because
this repository has no `code-gate` hook entry installed. The acceptance
re-runs A-1 in a consumer project that has one, against this release's own
packed artifact: the fast-lane lease owner editing src/ is allowed, and an
unplaceable caller is denied. The evidence is in the probe results.

That re-run turned up two things about the gate and the package rather than
about the batch mode, both recorded in the project's memory: the deny rule
is a raw prefix match, so a non-relative path bypasses it; and the
published layout only boots when the sub-packages sit nested under the
root, which a local install does not produce. Both are outside this slice
and left for their own.

Version level: patch. The interval v4.1.12..HEAD is 32 non-merge commits
(10 feat / 11 fix / 11 docs), and this release is purely additive - the new
`peaks batch` command group and the new batch and lint modules. No
existing CLI argument, no peaks-code step, no Gate A-G and no transition
state machine changes; the two shared paths this touches take an optional
argument and behave identically when it is absent.

The tracked size baseline gains no row: this release adds no file inside
the gated scope. Every ceiling is unchanged.