[KIM] Deliver a Phi-only integral-ion D11 tracer bullet

[krystophny]

What to build

Implement the smallest complete path through the new gyrokinetic integral transport formalism: a Phi-only ion D11 calculated by periodic KIM, exposed in the local result, and checked against the established drift-kinetic limit.

Use the Mathematica derivation as the algebraic oracle. Retain the complete susceptibility moment layout required by the final tensor now, so later slices extend the field contraction rather than redesigning storage.

Acceptance criteria

• The complete required moment set I_(ell,sigma)^(p,q), for p and q from 0 through 3, is available with documented species, radius, and harmonic indexing.
• A checked Mathematica verification/export artifact supplies the Phi-Phi D11 coefficients without creating a runtime Mathematica dependency.
• Generated coefficient data records the generator version or content hash.
• Periodic KIM calculates a real Phi-only ion D11 and returns it through the local-response contract.
• Exact/rational and high-precision sample points agree with the Mathematica oracle.
• A common phase rotation of the field leaves D11 unchanged.
• In the zero-FLR, ell=0, local diagonal limit with Bparallel=0, D11 agrees with the established drift-kinetic ion expression.
• Algebraic roundoff, Fourier/quadrature error, and asymptotic-limit error use separate tolerances.
• Production-size moment storage has a documented memory measurement.

Blocked by

• [KIM] Make nonzero cyclotron-harmonic support honest and internally consistent #258
• [KIM] Return a state-isolated periodic local response #285