[NPUW] Model builder: name projection MatMuls optimum-style for dynamic LoRA

Append "/MatMul" to the projection MatMul friendly name so GenAI's
dynamic-LoRA lora_state_* ids carry "MatMul"; NPUW's ReshapeToStatic only
pins the LoRA rank static for those, otherwise NPU compile throws
"to_shape was called on a dynamic shape".

Author: dylanneve1

src/plugins/intel_npu/tests/functional/behavior/npuw/test_engine/models/model_builder.cpp

@@ -72,7 +72,8 @@ ov::Output<ov::Node> make_linear(const ov::Output<ov::Node>& input,
     auto weight_output = weight_fn(name + ".weight", ov::Shape{out_features, in_features}, precision);
 
     auto matmul = std::make_shared<ov::opset11::MatMul>(input, weight_output, false, true);
-    matmul->set_friendly_name(name);
+    // optimum-style name so GenAI dynamic-LoRA state ids carry "MatMul" (NPUW pins rank static on it).
+    matmul->set_friendly_name(name + "/MatMul");
 
     ov::Output<ov::Node> result = matmul->output(0);