Complete rewrite of _build_nam_model and _build_wavenet to handle:
- SlimmableContainer (A2): pick submodel by quality, recurse into WaveNet
- WaveNet: proper dilated convs with causal padding, 1x1 layer1x1 post-conv
- Linear: simple pass-through with gain/bias
Weight import matches NAM export order:
rechannel -> per-layer(conv w+b, input_mixer w, layer1x1 w+b) -> head_rechannel w+b -> optional head -> head_scale
Also fixes MOCK_PRESETS in frontend to match actual factory preset names.
shawn
6e07aa2b38