Match header wordmark weight to the React site

The Go header rendered "arewefastyet" with font-light (300). React used
font-semilight, an undefined Tailwind class that generates no CSS, so the
wordmark fell back to the heading reset's inherited normal weight (400).
Use font-normal so the Go wordmark matches.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Arthur Schreiber <arthur@planetscale.com>

Author: arthurschreiber

go/server/templates/web/partials/navbar.html

@@ -3,7 +3,7 @@
   <div class="w-full bg-background z-[49] flex justify-between lg:justify-center p-4 border-b border-border">
     <a href="/" class="flex flex-1 gap-x-2 items-center">
       <img src="/static/logo.png" class="h-[2em] shrink-0" alt="logo" />
-      <h1 class="font-light text-lg md:hidden lg:block">arewefastyet</h1>
+      <h1 class="font-normal text-lg md:hidden lg:block">arewefastyet</h1>
     </a>
 
     <div class="flex justify-end items-center gap-x-4 lg:justify-end lg:flex-shrink-0 ml-8">