docs(website): serve Umami first-party from umami.relplay.org

Brave Shields (and similar blockers) block Umami only as a third-party
request, so point the tracker at umami.relplay.org — a proxied CNAME to
the Umami server that's first-party to relplay.org — instead of the
server's own host. Same Website ID; the data endpoint follows the script
host, so no other change. Privacy page updated to name the new host, and
a comment in astro.config.mjs records why it's a relplay.org subdomain.

website/astro.config.mjs

@@ -62,6 +62,10 @@ export default defineConfig({
 				// Website ID is public by design (it ships in every page). The script
 				// loads from the Umami host, which also becomes the data destination,
 				// so no `data-host-url` is needed.
+				//   - Served first-party under `umami.relplay.org` (a proxied CNAME to
+				//     the Umami server) rather than the server's own host: privacy
+				//     blockers (e.g. Brave Shields) block Umami only as a *third-party*
+				//     request, so a same-registrable-domain host is not flagged.
 				//   - data-domains: only run on the production apex, so the
 				//     `website.relplay.pages.dev` preview and `staging.relplay.org`
 				//     don't pollute the stats.
@@ -71,7 +75,7 @@ export default defineConfig({
 					tag: 'script',
 					attrs: {
 						defer: true,
-						src: 'https://umami.oliversturm.com/script.js',
+						src: 'https://umami.relplay.org/script.js',
 						'data-website-id': 'fd77cfa5-cffe-4fc8-addb-1c6d7b6d9939',
 						'data-domains': 'relplay.org',
 						'data-do-not-track': true,

website/src/content/docs/privacy.md

@@ -11,7 +11,7 @@ visitors. We keep the analytics deliberately minimal.
 
 We measure aggregate usage with **[Umami](https://umami.is/)**, a
 privacy-friendly analytics tool that we **host ourselves** (on
-`umami.oliversturm.com`). Nothing is sent to a third-party advertising
+`umami.relplay.org`). Nothing is sent to a third-party advertising
 network.
 
 For each page view we record: