Add standalone mode for sx-web.org deployment

- SX_STANDALONE=true env var: no OAuth, no root header, no cross-service
  fragments. Same image runs in both rose-ash cooperative and standalone.
- Factory: added no_oauth parameter to create_base_app()
- Standalone layout defcomps skip ~root-header-auto/~root-mobile-auto
- Fixed Dockerfile: was missing sx/sx/ component directory copy
- CI: deploys sx-web swarm stack on main branch when sx changes
- Stack config at ~/sx-web/ (Caddy → sx_docs, Redis)

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

sx/Dockerfile

@@ -26,6 +26,7 @@ COPY sx/ ./sx-app-tmp/
 RUN cp -r sx-app-tmp/app.py sx-app-tmp/path_setup.py \
          sx-app-tmp/bp sx-app-tmp/sxc sx-app-tmp/services \
          sx-app-tmp/content sx-app-tmp/__init__.py ./ 2>/dev/null || true && \
+    ([ -d sx-app-tmp/sx ] && cp -r sx-app-tmp/sx ./sx || true) && \
     rm -rf sx-app-tmp
 
 # Sibling models for cross-domain SQLAlchemy imports