fix: use /metrics on the main router (#255)

Signed-off-by: Chris Gianelloni <wolf31o2@blinklabs.io>

internal/api/static/index.html

@@ -57,7 +57,7 @@
         <div
           id="metrics-container"
           class="flex items-center flex-wrap font-mono gap-4 whitespace-pre mb-4"
-          hx-get="javascript:window.location.protocol + '//' + window.location.hostname + ':8081/'"
+          hx-get="/metrics"
           hx-trigger="load, every 1s"
           hx-swap="innerHTML"
         >