fix: bump content max-width from 4xl to 6xl (896px → 1152px)

Better utilizes screen real estate on 1440p and 1080p monitors.
Mobile and tablet remain full-width (constraint only at lg+).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: luisxcam

src/pages/Index.tsx

@@ -51,7 +51,7 @@ const Index = () => {
         </div>
 
         {/* Content */}
-        <div className="p-6 lg:p-10 pt-16 lg:pt-6 pb-10 lg:max-w-4xl">
+        <div className="p-6 lg:p-10 pt-16 lg:pt-6 pb-10 lg:max-w-6xl">
           {sections[activeSection]}
         </div>