feat(proxy): support external TLS termination

compose.yaml

@@ -121,7 +121,7 @@ services:
     image: caddy:2.10.2-alpine
     environment:
       DOMAIN: ${DOMAIN:?set DOMAIN in .env}
-      SITE_ADDRESS: ${DOMAIN:?set DOMAIN in .env}
+      SITE_ADDRESS: ${CADDY_SITE_ADDRESS:-${DOMAIN:?set DOMAIN in .env}}
       ACME_EMAIL: ${ACME_EMAIL:?set ACME_EMAIL in .env}
     ports:
       - ${HTTP_PORT:-80}:80