[QL-Balance] Couple one periodic KIM mode with compact global embedding

[krystophny]

What to build

Run one stationary QL-Balance mode through periodic KIM instead of global KIM. Embed the returned local response into QL-Balance's global radial grid with a bounded smooth transition, calculate drift-kinetic electron transport from the same physical local fields, and consume KIM's integral ion tensor.

The production path must keep local validity explicit. It must not extrapolate periodic edge artifacts over the plasma or create an electric field by differentiating a tapered potential.

Acceptance criteria

• Selecting the coupled periodic model invokes periodic KIM and does not require a global KIM field solution.
• QL-Balance passes its current global profiles and signed mode to the local KIM request.
• A documented compact transition equals one in the trusted core, has the declared endpoint smoothness, and is zero outside bounded support.
• Physical electric and misalignment-field components are derived locally before transition weighting; no derivative-of-window field is introduced.
• Cancelling misalignment components retain a common transition and their relative complex phase.
• A local transport tensor is embedded as w squared times the local tensor and remains positive semidefinite within tolerance.
• Electrons use only the established Heyn/Markl drift-kinetic coefficients.
• Ions use only the KIM integral tensor in production mode.
• Br, B-parallel, electric fields, species current, transition metadata, and separate electron/ion tensors are available in diagnostic output.
• Hard-zero and bounded extrapolation policies, if retained, require explicit diagnostic selection and are not production defaults.
• A stationary one-mode integration test produces finite localized coefficients and zero perturbative transport outside support.

Blocked by

• Preserve signed m, n, and q when locating KIM/QL-Balance resonances #231
• [KIM] Complete all B-parallel integral ion transport channels #289