Set the nav wordmark in the display face

The "Setup Agent" brand mark was the only Inter element in the header
(nav links and version badge are mono), reading as a generic bold sans.
Render it in Playfair Display 900 so it echoes the hero title and section
headings and belongs to the site's type system.

Author: Codegass

website/css/style.css

@@ -91,11 +91,11 @@ header.g {
 }
 
 .nav-brand h2 {
-  font-family: var(--sans);
-  font-size: 1.75rem;
-  font-weight: 700;
-  line-height: 1;
-  letter-spacing: 0.03em;
+  font-family: var(--display);
+  font-size: 1.6rem;
+  font-weight: 900;
+  line-height: 0.95;
+  letter-spacing: -0.01em;
 }
 
 .nav-link {