fix(caddy): route relay WebSocket traffic to relay container

Add /relay* location block to Caddyfile template so that NetBird relay
WebSocket connections (rels://) are correctly forwarded to the relay
container instead of falling through to the dashboard handler.

Without this fix, all relay WebSocket connections silently hit the
dashboard container, causing STUN/relay connectivity failures for all
deployed NetBird instances.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/Caddyfile.j2

@@ -29,6 +29,11 @@
 		}
 	}
 
+	# NetBird Relay WebSocket (rels://)
+	handle /relay* {
+		reverse_proxy netbird-{{ subdomain }}-relay:80
+	}
+
 	# Default: NetBird Dashboard
 	handle {
 		reverse_proxy netbird-{{ subdomain }}-dashboard:80