feat: add ideogram4 support (#1609)

examples/common/common.h

@@ -123,6 +123,7 @@ struct SDContextParams {
     std::string llm_vision_path;
     std::string diffusion_model_path;
     std::string high_noise_diffusion_model_path;
+    std::string uncond_diffusion_model_path;
     std::string embeddings_connectors_path;
     std::string vae_path;
     std::string vae_format = "auto";