[KIM] Complete all B-parallel integral ion transport channels

[krystophny]

What to build

Extend the integral ion tensor to the five ordered channels that contain B-parallel: Bparallel-Bparallel and both directions of its cross terms with Phi and Br. The delivered tensor must contain all nine ordered pairs of the three-field vector and remain traceable to the Mathematica derivation.

Acceptance criteria

• D11, D12, D21, and D22 include all nine ordered pairs of Phi, Br, and B-parallel.
• Every added coefficient-polynomial family agrees with the Mathematica oracle at exact/rational and high-precision sample points.
• Each B-parallel field-pair insertion is tested independently against a direct reference contraction.
• Setting B-parallel to zero removes exactly the five associated ordered/cross contributions and reproduces the complete Phi/Br tensor.
• A B-parallel-only long-wavelength test reproduces the analytic magnetic-moment term, including relative phase and species-sign conventions.
• Hermiticity, Onsager symmetry, phase invariance, and positive-semidefinite checks pass with declared tolerances.
• Cyclotron-harmonic and finite-Larmor-radius convergence tests include a nonzero B-parallel case.
• Channel-resolved diagnostics are available in test/debug output without changing the production result contract.

Blocked by

• [KIM] Complete the Phi/Br integral ion transport tensor #287
• [KIM][KiLCA] Carry the B-parallel vacuum drive through the periodic response #288