ipx-web's spans are named for the request (#286)

Caddy named every span ipx-web, so Tempo's lists and trace view showed the
same name for each request. Caddy 2.11 takes placeholders in the span name:
now the method and path, as ipx names its own. The prod check's span list
shows a span's url.path when it has no route.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/Caddyfile

@@ -30,7 +30,9 @@
 
 (tracing-on) {
 	tracing {
-		span ipx-web
+		# Named for the request, as ipx names its own (#286): one name for all left every span in
+		# Tempo looking the same.
+		span "{http.request.method} {http.request.uri.path}"
 	}
 }
 (tracing-off) {