fix(webapp): declare the non.geist font modules for typecheck

The side-effect CSS imports in root.tsx have no type declarations, so
tsc fails with TS2882.

Author: kathiekiwi

apps/webapp/remix.env.d.ts

@@ -1,3 +1,7 @@
 /// <reference types="@remix-run/dev" />
 /// <reference types="vite/client" />
 /// <reference types="@remix-run/node/globals" />
+
+// Font packages that resolve to CSS — imported for their side effect only.
+declare module "non.geist";
+declare module "non.geist/mono";