* 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 the sizes in size_t.
* mtmd: fill M-RoPE positions by whole merge tiles
The position loops of the Qwen-VL, GLM, PaddleOCR and Qwen2.5-VL
encoders hardcode a 2x2 merge inside a stride of n_merge, so a patch
grid that is not a multiple of the merge writes past the positions
buffer. Iterate over whole merge tiles with n_merge inner steps, which
bounds the writes by the patch count and gives the same positions on
aligned grids.
PaddleOCR also requires a merge aligned image at graph build, as the
Qwen-VL family already does.
Pascal
