mtmd: refactor preprocessing + support max/min pixels (#16878)

mtmd: refactor preprocessing + support max/min pixels (#16878)

* mtmd: refactor preprocessing + support max/min pixels

* fix mlp type

* implement mix/max pixels

* improve hparams

* better image preproc for qwen

* fix

* fix out of bound composite

* fix (2)

* fix token calculation

* get_merge_kernel_size()

* fix llama4 and lfm2

* gonna fix them all

* use simple resize for qwen

* qwen: increase min tokens

* no resize if dst size == src size

* restore to initial min/max tokens value for qwen