Use min/max dynamic shape bounds for forward inputs/outputs

Backfill constant metadata method values in config.json from .pte

Rename 350m/mlx/lfm2_5_350m_mlx_4w_v2.pte to 350m/mlx/lfm_2_5_350m_mlx_int4.pte

Upload lfm2_5_350m_mlx_4w_v2.pte

Create mlx/config.json

Add spec-compliant config.json files

Refresh lfm-2.5 config.json files for VL/text split

Fix lfm-2.5 layout: distinguish VL from text + colocate tokenizers

Add spec-compliant config.json files

Restructure to MODEL_SPEC.md convention