flax

777b50a8 - Use linen_vars_to_nnx_attrs in ToLinen variable restoration

Use linen_vars_to_nnx_attrs in ToLinen variable restoration Refactor ToLinen.__call__ to use linen_vars_to_nnx_attrs for converting Linen variables back to NNX state, replacing manual AxisMetadata unboxing and merge_state. PiperOrigin-RevId: 875328492