Join railway-caddy network pinscope_pinscope after compose up.

Caddy reverse_proxies periscope-frontend by Docker DNS and is not on
the compose project bridge; attach the app containers so HTTPS stops 502.

docker-compose.yml

@@ -1,7 +1,8 @@
 # Canonical compose project on the VPS is "periscope" (not the GitHub
 # clone folder name "pinscope"). Bind mounts stay relative to the checkout.
-# Keep the Docker network name pinscope_periscope so host Caddy/nginx that
-# joined the pre-rename network can still reach these containers by DNS.
+# Host Caddy (railway-caddy) lives on Docker network pinscope_pinscope and
+# reverse_proxies periscope-frontend:3000 / periscope-backend:8080. The
+# update script connects these containers to that network after up.
 name: periscope
 
 services:
@@ -61,5 +62,4 @@ services:
 
 networks:
   periscope:
-    name: pinscope_periscope
     driver: bridge