docs(cli): add hero image

Author: nucliweb

pages/CLI.mdx

@@ -6,6 +6,21 @@ type: guide
 
 Run curated WebPerf Snippets headlessly via Playwright. Diagnose Core Web Vitals beyond what Lighthouse exposes and gate CI on real performance budgets.
 
+<picture style={{ marginTop: "20px", display: "block" }}>
+  <img
+    width="1200"
+    height="749"
+    sizes="85vw"
+    srcSet="https://res.cloudinary.com/nucliweb/image/upload/c_scale,f_auto,q_auto,w_600/v1777928598/webperf-snippets/webperf-snippets-CLI.png 600w,
+            https://res.cloudinary.com/nucliweb/image/upload/c_scale,f_auto,q_auto,w_1200/v1777928598/webperf-snippets/webperf-snippets-CLI.png 1200w"
+    src="https://res.cloudinary.com/nucliweb/image/upload/c_scale,f_auto,q_auto,w_342/v1777928598/webperf-snippets/webperf-snippets-CLI.png"
+    loading="eager"
+    decoding="sync"
+    fetchpriority="high"
+    alt="WebPerf Snippets CLI"
+  />
+</picture>
+
 ## Why
 
 Lighthouse gives you a score. The DevTools snippets give you the _diagnosis_ — TTFB / Resource Load Delay / Element Render Delay sub-parts, LoAF script attribution, render-blocking resources, and more. The CLI runs the same curated snippets in a headless browser so you can: