Port of Qwen3-VL support from mainline (#883)

* Port of Qwen3-VL for latest ik_llama.cpp

- convert_hf_to_gguf.py - Not touched, use llama.cpp to convert model instead
- sysl and metal support for imrope not added
- Vulkan support for imrope not tested
- Code not tested

* Bugfix n_embd was declared multiple times

https://github.com/ikawrakow/ik_llama.cpp/pull/883#issuecomment-3471179655

* Fix n_embd issue with qwen3vl

* model.output tensor not required

https://github.com/ikawrakow/ik_llama.cpp/pull/883#discussion_r2480388389

* Improved logic for qkv combined tensors

59ceaf8fcb (r2480395800)
59ceaf8fcb (r2480398187)

* Fix n_embd for merge_qkv() + cleaner code

https://github.com/ikawrakow/ik_llama.cpp/pull/883#discussion_r2481227395

* Revert TENSOR_NOT_REQUIRED

src/llama-hparams.h

@@ -110,7 +110,10 @@ struct llama_hparams {
     uint32_t n_no_rope_layer_step    = 4;
     uint32_t n_attn_temp_floor_scale = 8192;
     float    f_attn_temp_scale       = 0.1;
-
+	
+	// qwen3vl deepstack
+    uint32_t n_deepstack_layers = 0;
+	
     // needed by encoder-decoder models (e.g. T5, FLAN-T5)
     // ref: https://github.com/ggerganov/llama.cpp/pull/8141
     llama_token dec_start_token_id = -1;