Function reduce_for_view 

pub fn reduce_for_view(
    field: &HostPhasorField,
    source_sampling_certificate: SamplingCertificate,
    observable: Observable,
    phase_floor: f64,
    target_rows: usize,
    target_columns: usize,
    rule: ReductionRule,
) -> Result<ScalarProjection, ProjectionError>

Reduces a phasor field onto a no-larger target grid using one named detector.

Each target axis is an integer partition of its source axis. The Cartesian product of those partitions covers every source cell exactly once, including odd dimensions and non-divisible target shapes. Detail mode accepts only the identity shape. Detector rules are deliberately paired with the observables whose semantics they preserve; wrapped phase angles are never averaged.