common, mtmd: bound control vector layer indices and M-RoPE position loops ( #31336 ) common: bound control vector layer indices by the model layer count A direction tensor layer index is parsed from the tensor name with no upper bound, and the buffer size and write offset are computed in int. A large index overflows both, so the accumulation writes before the start of the buffer. Pass the model layer count to the loader, reject indices above it like the existing zero index check, and compute th