Phase 3 of the Stratification milestone (contract C28). `aura run` now
shape-dispatches on the loaded blueprint: a `bias` output takes the
existing strategy path (wrap_r + R evaluation), byte-identical; a
blueprint that declares taps but exposes no `bias` runs bare via the new
`run_measurement` (bootstrap, run, drain the declared taps) with no
SimBroker, no risk executor, and no per-cycle equity/exposure/r
recorders; a blueprint exposing neither is refused. This gives the
measurement layer its own run verb and removes the O(cycles) recording
retention (the measured ~2 GB peak RSS over 12y UK100 M1) the mandatory
R scaffold imposed on a measurement-shaped run.
A new `MeasurementReport { manifest, taps }` (aura-engine::report, beside
RunReport) is the stdout/record shape — no R metrics, since a bare run
has no broker. The manifest's `broker` carries an interim "measurement"
sentinel; the honest `Option<String>` model is deferred to the #147
metric-genericity block, keeping this phase #147-free and the
strategy-path C18 goldens byte-identical.
`run_signal_r` is untouched (the tap machinery is duplicated into
`run_measurement`, not extracted). The measurement arm's closed-blueprint
guard uses `signal.param_space()` rather than `blueprint_axis_probe`,
which welds wrap_r and would panic on a no-`bias` signal.
refs #286
claude
34ff539143