Migrating to 0.7

DC OPF problem data moved from powerio-matrix to powerio-prob. powerio-matrix now owns generic network projections. It does not depend on or reexport powerio-prob.

Replace these 0.6 imports:

use powerio_matrix::{OpfInstance, Units, build_opf_instance};
use powerio_matrix::{DcOpfOptions, write_dcopf_bundle};

with:

use powerio_prob::{DcOpfInstance, DcOpfOptions, Units, build_dc_opf_instance};
use powerio_prob::matrix::{DcOpfBundleOptions, write_dcopf_bundle};

DcOpfInstance stores generators in generator space. Call DcOpfInstance::nodal_generator_data only when a bus space formulation is required; it aggregates the generators at each bus.

The default powerio-prob feature set contains no sparse matrix dependency. Enable matrix for incidence, Laplacian, flow, generator map, and bundle output:

[dependencies]
powerio-prob = { version = "0.7", features = ["matrix"] }

powerio_prob::matrix::write_dcopf_bundle accepts an assembled instance. Cost policy handling happens before assembly. The writer does not read the source network again.

Solver formulations and KKT operators are not part of powerio-prob. Build them in the solver from the indexed instance and optional matrix projections.