Closes the remaining doable items from the 2026-05-11 training-pipeline audit:
#6 (CSI format default = 56-sc / 1 NIC) + #7 (multi-band 168-sc mesh not in
config): new `TrainingConfig::for_subcarriers(native, target)` plus named
presets `mmfi()` (114→56), `ht40_192()` (≈192-sc ESP32 HT40 → 56) and
`multiband_168()` (168-sc ADR-078 multi-band mesh → 56). Non-MM-Fi CSI shapes
are now first-class instead of requiring manual `native_subcarriers` /
`num_subcarriers` overrides; the field docs list the supported source counts
and the multi-NIC mapping (a 2–3-node mesh currently rides on `n_rx` until a
dedicated node dimension lands). Model input width stays `num_subcarriers`; the
presets only vary the resampling input.
#4 (proof.rs uses synthetic data): reframed — a deterministic proof *must* use
a reproducible source, so `verify-training` correctly stays on
`SyntheticCsiDataset`. The real gap was that nothing exercised the on-disk
`MmFiDataset` path. New `tests/test_real_loader.rs` writes synthetic CSI to
`.npy` files in the `MmFiDataset::discover` layout, loads it back, and checks
the resulting `CsiSample` — covering the no-interp case, the
subcarrier-interpolation branch, and the empty-root case. Adds `ndarray` /
`ndarray-npy` as dev-deps for the fixture writing.
cargo check + cargo test -p wifi-densepose-train --no-default-features: clean,
all existing tests green, 3 new loader tests + the updated config doctest pass.
Purely additive — no model-shape change, no tch-module change.
c604ca1150