Hardcode port 8080, extract nginx config, fix host row overflow

- Nginx: extract config from Dockerfile heredoc to nginx.conf, hardcode
  port 8080, remove envsubst templating
- Host row: add bottom padding so stats line stays within the row well

src/main.js

@@ -554,7 +554,7 @@ function hostRowHTML(host, index, showPin = true) {
       <div class="flex items-center gap-4 min-w-0">
         ${pinBtn}
         <div class="w-[480px] flex-shrink relative min-w-0">
-          <div class="max-w-[55%]">
+          <div class="max-w-[55%] pb-5">
             <div class="flex items-center gap-2">
               <div class="w-3 h-3 rounded-full flex-shrink-0" style="background-color: ${latencyHex(null)}"></div>
               <span class="font-medium text-white truncate">${host.name}</span>