Steady stream-power landscapes: existence, constructive local uniqueness, and singular limits; with a companion channel audit

Unrefereed analytical candidate: small-erosion coupled steady existence, constructive local nonradial uniqueness under constant forcing and a flow-growth margin, quantitative radial theory, and a separate conditional channel-compatibility audit. AI-assisted revision and producer computational checks do not establish human specialist acceptance, formal proof verification, priority or REF status. Original prose/data CC0-1.0; original code MIT; third-party papers and supplied full audits are not redistributed.