Add font-display: swap to docs font declarations (#35910)

This PR adds the `font-display: swap` property to all GT America font-face declarations in the docs package's custom.css file. This change improves font loading behavior by displaying a fallback font immediately while the custom font is still loading, which improves perceived performance and prevents "invisible text" during page load.

GitOrigin-RevId: 63e8080cf6fcbe17fc9afd59f9782e0451003215

Author: devin-ai-integration[bot]

npm-packages/docs/src/css/custom.css

@@ -12,21 +12,25 @@
 @font-face {
   font-family: "GT America";
   font-weight: 400;
+  font-display: swap;
   src: url(https://docs.convex.dev/fonts/GT-America-Standard-Regular.woff2);
 }
 @font-face {
   font-family: "GT America";
   font-weight: 500;
+  font-display: swap;
   src: url(https://docs.convex.dev/fonts/GT-America-Standard-Medium.woff2);
 }
 @font-face {
   font-family: "GT America";
   font-weight: 700;
+  font-display: swap;
   src: url(https://docs.convex.dev/fonts/GT-America-Standard-Bold.woff2);
 }
 @font-face {
   font-family: "GT America";
   font-weight: 900;
+  font-display: swap;
   src: url(https://docs.convex.dev/fonts/GT-America-Standard-Black.woff2);
 }