model : add control vector support where missing (#20653)

* Add control vector functions to qwen3.5 and qwen-next models

* Add missing cvec compatibility to the rest of the models

* Adjust comments and formatting

* cleanup

* whitespace

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

src/models/smallthinker.cpp

@@ -101,6 +101,7 @@ llm_build_smallthinker<iswa>::llm_build_smallthinker(const llama_model & model,
         cur = ffn_out;
 
         cur = ggml_add(ctx0, cur, ffn_inp);
+
         cur = build_cvec(cur, il);
         cb(cur, "l_out", il);