Add configurable Plausible analytics

Co-authored-by: Cursor <cursoragent@cursor.com>

web/src/layouts/Base.astro

@@ -130,6 +130,9 @@ const i18nPayload = JSON.stringify({ locale, catalog: clientCatalog(locale) }).r
  */
 const imageUrl = new URL(image, site).href;
 
+const plausibleUrl = import.meta.env.PLAUSIBLE_URL;
+const plausibleDomain = import.meta.env.PLAUSIBLE_DOMAIN;
+
 /**
  * This page's JSON-LD, assembled here and nowhere else.
  *
@@ -267,6 +270,9 @@ const noscriptMotion =
     {graph.length > 0 && (
       <script type="application/ld+json" is:inline set:html={serializeGraph(graph)} />
     )}
+    {plausibleUrl && plausibleDomain && (
+      <script is:inline defer data-domain={plausibleDomain} src={plausibleUrl}></script>
+    )}
   </head>
   <body>
     {/*