[KAMEL] Ship and validate the production periodic integral-transport workflow

[krystophny]

What to build

Turn the completed periodic KIM and QL-Balance slices into a reproducible KAMEL workflow. Expose validated configuration through the Fortran and Python entry points, record complete HDF5 provenance, add end-to-end golden cases, and produce the scientific convergence and performance report required for human acceptance.

This implementation work is AFK-ready. Declaring the new physics workflow production-accepted remains an explicit human scientific sign-off after the report is available.

Acceptance criteria

• Configuration explicitly selects periodic KIM, harmonic bounds, drift-kinetic electrons, integral ions, B-parallel source, compact-transition parameters, target-current guards, and benchmark mode.
• Unsupported model combinations fail validation instead of falling through hidden hard-coded branches.
• Python orchestration can configure and execute the complete coupled workflow.
• HDF5 output records per-mode local windows, transition metadata, Br, B-parallel, electric fields, species current, unscaled/scaled tensors, shielding history, model names, Fourier convention, and algebra-generator hash.
• One small production golden case covers periodic KIM, both species policies, B-parallel, target-current normalization, profile evolution, and restart.
• A separate golden case covers the old/new ion drift limit and records all four residuals.
• Automated scans cover Fourier/radial resolution, periodic-core and transition width, cyclotron harmonics, finite-Larmor-radius convergence, B-parallel channel isolation, and time-step refinement.
• A representative central-layer comparison against global KIM is reported without treating global agreement as the sole correctness oracle.
• Periodic coupling wall time and memory are measured against global KIM for representative target workloads and demonstrate the intended speed advantage.
• Existing KiLCA, global-KIM, and default QL-Balance regression suites remain green.
• User documentation explains the model boundary, validity region, normalization, benchmark, diagnostics, and restart procedure.
• A review artifact summarizes tolerances, residuals, taper sensitivity, convergence, performance, and remaining scientific uncertainty for human sign-off.

Blocked by

• [KAMEL] Benchmark integral ions against the drift-kinetic limit #291
• [QL-Balance] Evolve and restart target-current shielding amplitudes #294