model: support MiMo-V2-Flash (#18328)

* mimov2: convert ok

* rename mimov2 --> mimo2

* fix conversion

* runnable not incorrect

* use sink

* add_sliding_window_pattern

* add swa and per-layer n_head_kv

* correct params

* somewhat working

* correct gating func

* nits

* mimo2: wire RMS eps + MoE bias + converter guards

* add co-author

Co-authored-by: Aaryan-Kapoor <Aaryan-Kapoor@users.noreply.github.com>

* use add_rope_freq_base_swa

---------

Co-authored-by: Aaryan Kapoor <aaryankapoor2006@gmail.com>
Co-authored-by: Aaryan-Kapoor <Aaryan-Kapoor@users.noreply.github.com>

src/CMakeLists.txt

@@ -88,6 +88,7 @@ add_library(llama
             models/llama-iswa.cpp
             models/llama.cpp
             models/mamba.cpp
+            models/mimo2-iswa.cpp
             models/minicpm3.cpp
             models/minimax-m2.cpp
             models/modern-bert.cpp