sd: sync to master-637-ef92a00

[wbruna]

On top of #2213 . LTX 2.3 support, some sampler changes, and a vocab file refactor.

Several added files:

otherarch/sdcpp/guidance.cpp
otherarch/sdcpp/guidance.h
otherarch/sdcpp/ltx_audio_vae.h
otherarch/sdcpp/ltx_vae.hpp
otherarch/sdcpp/tokenizers/gemma_tokenizer.cpp
otherarch/sdcpp/tokenizers/gemma_tokenizer.h
otherarch/sdcpp/tokenizers/vocab/clip_merges.hpp
otherarch/sdcpp/tokenizers/vocab/gemma_merges.hpp
otherarch/sdcpp/tokenizers/vocab/gemma_vocab.hpp
otherarch/sdcpp/tokenizers/vocab/mistral_merges.hpp
otherarch/sdcpp/tokenizers/vocab/mistral_vocab.hpp
otherarch/sdcpp/tokenizers/vocab/qwen_merges.hpp
otherarch/sdcpp/tokenizers/vocab/t5.hpp

and a few removed:

otherarch/sdcpp/tokenizers/vocab/clip_t5.hpp
otherarch/sdcpp/tokenizers/vocab/mistral.hpp
otherarch/sdcpp/tokenizers/vocab/qwen.hpp

so I ended up sorting and rebuilding the source file list.

To fix the linking errors, I've added load_gemma_merges and load_gemma_vocab_json functions with search+replace from the mistral ones.

Edit: updated to master-633-5b0267e to get a few new fixes.

Edit 2: updated to master-637-ef92a00 for more LTX stuff, and a LoRA offloading performance fix.

[LostRuins]

Alright now that the other PR is merged, this is next on the list after I test out the gemma vocab extraction and minifications