Add opennotebook.rnotes.online route and iframe embedding support

Adds Traefik router for rnotes.online subdomain alias, mounts Streamlit
config to disable XSRF/CORS for cross-origin iframe embedding in rNotes.

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

.streamlit/config.toml

@@ -0,0 +1,6 @@
+[server]
+enableXsrfProtection = false
+enableCORS = false
+
+[browser]
+gatherUsageStats = false

docker-compose.yml

@@ -11,6 +11,7 @@ services:
     volumes:
       - ./notebook_data:/app/data
       - ./surreal_data:/mydata
+      - ./.streamlit/config.toml:/app/.streamlit/config.toml:ro
     labels:
       - "traefik.enable=true"
       - "traefik.docker.network=traefik-public"
@@ -24,6 +25,10 @@ services:
       - "traefik.http.routers.open-notebook-api.entrypoints=web"
       - "traefik.http.routers.open-notebook-api.service=open-notebook-api"
       - "traefik.http.services.open-notebook-api.loadbalancer.server.port=5055"
+      # rnotes.online subdomain alias
+      - "traefik.http.routers.open-notebook-rnotes.rule=Host(`opennotebook.rnotes.online`)"
+      - "traefik.http.routers.open-notebook-rnotes.entrypoints=web"
+      - "traefik.http.routers.open-notebook-rnotes.service=open-notebook"
     networks:
       - traefik-public
       - ai-internal