Latest b9274 Addresses MTP VRAM leak

B9274

I have been having an issue with MTP models unloading after a couple minutes of use. Can't figure out why. Anyways z I don't think this is relevant to that but I did observe the vram creep so hopefully this helps.

server : free draft/MTP resources on sleep to fix VRAM leak (#23461)

The destroy() function in server_context_impl only cleaned up the main model and context (via llama_init.reset()) but did not free the speculative decoder (spec), draft context (ctx_dft), or draft model (model_dft).

For MTP (Multi-Token Prediction) models, ctx_dft holds GPU-allocated resources (KV cache, compute buffers) that are not freed when entering the sleeping state. On each sleep/resume cycle, new resources are allocated without the old ones being freed, leading to a VRAM leak that eventually crashes the server with out-of-memory errors.

Fix by explicitly resetting spec, ctx_dft, and model_dft in destroy() before resetting llama_init, ensuring proper cleanup order to avoid use-after-free.