Adjust preview for dark mode and light mode (#250)

* Adjust preview for dark mode and light mode

picture element for better display based on color scheme.

* Rounded

* Update image alt text in README.md

Author: austenstone

README.md

@@ -4,8 +4,11 @@ InferenceMAX™ runs our suite of benchmarks every night, continually re-benchma
 
 [Full Article Write Up for InferenceMAXv1](https://newsletter.semianalysis.com/p/inferencemax-open-source-inference)
 
-<img width="1094" height="697" alt="image" src="https://github.com/user-attachments/assets/752390b5-7ba2-4d34-a344-11a14be15204" />
-
+<picture>
+  <source media="(prefers-color-scheme: dark)" srcset="https://github.com/user-attachments/assets/06966bbc-ebc8-4b3f-9201-d7f2628180cc">
+  <source media="(prefers-color-scheme: light)" srcset="https://github.com/user-attachments/assets/e78a2789-f65e-4315-af59-a4de6de73488">
+  <img alt="InferenceMAX benchmark results visualization" src="https://github.com/user-attachments/assets/e78a2789-f65e-4315-af59-a4de6de73488">
+</picture>
 
 ## Why?