feat(analytics): integrate Umami analytics

This commit introduces Umami analytics for website usage tracking.

- Adds a new `analytics.js` file to the `public` directory to load the Umami tracking script.
- Updates `nuxt.config.ts` to inject this script into the document head and configure the page title.

Additionally, this commit fixes the referrer note display by removing a hardcoded prefix.

public/analytics.js

@@ -0,0 +1,10 @@
+(function () {
+  const UMAMI_SCRIPT_JS = "https://umami.tootaio.com/script.js";
+  const UMAMI_ID = "dcb8b7ff-408c-4843-9a1a-c01da704ffc1";
+
+  var script = document.createElement("script");
+  script.async = true;
+  script.src = UMAMI_SCRIPT_JS;
+  script.setAttribute("data-website-id", UMAMI_ID);
+  document.head.appendChild(script);
+})();