Docs: make Samples the primary hero CTA, drop GitHub button

Hero buttons are now Samples | Tutorial | VSCode | Agent skill, with
Samples as the primary action. GitHub remains in the top nav.

Co-Authored-By: Claude Fable 5 <[email protected]>

Author: dzikowski

docs/index.html

@@ -50,10 +50,8 @@
     <header>
         <h1>J<span class="jaiph-accent">ai</span>ph</h1>
         <div class="hero-cta">
-            <a href="/tutorials/first-workflow" rel="noopener noreferrer" class="button button-primary">Tutorial</a>
-            <a href="#samples" rel="noopener noreferrer" class="button button-dark">Samples</a>
-            <a href="https://github.com/jaiphlang/jaiph" target="_blank" rel="noopener noreferrer"
-                class="button button-dark">GitHub</a>
+            <a href="#samples" rel="noopener noreferrer" class="button button-primary">Samples</a>
+            <a href="/tutorials/first-workflow" rel="noopener noreferrer" class="button button-dark">Tutorial</a>
             <a href="https://marketplace.visualstudio.com/items?itemName=jaiph.jaiph-syntax-vscode" target="_blank"
                 rel="noopener noreferrer" class="button button-dark no-mobile">VSCode</a>
             <a href="https://raw.githubusercontent.com/jaiphlang/jaiph/refs/heads/main/docs/jaiph-skill.md"