feat(cluster0): add Janus SFU deploy script and graph gzip smoke test

deploy-janus-sfu.sh installs Janus on cast02, writes signaling config, and templates CAST02_IP into nginx; populate gains --phase sfu.

Co-authored-by: Cursor <cursoragent@cursor.com>

sim/cluster0/lab-seeds/backend/scripts/test_graphs_api.sh

@@ -76,7 +76,24 @@ echo
 echo "…"
 
 if [[ "${upload_code}" != "200" ]]; then
-  echo "FAIL: upload expected 200" >&2
+  echo "FAIL: plain upload expected 200" >&2
+  exit 1
+fi
+
+sid_gzip="smoke-graph-gzip-$(date +%s)"
+payload_gzip="${payload/${sid}/${sid_gzip}}"
+echo "POST ${UPLOAD_URL} (gzip, device-style)"
+gzip_upload_code="$(curl -sS -o /tmp/graph_upload_gzip_resp.json -w '%{http_code}' \
+  -H 'Content-Type: application/json' \
+  -H 'Content-Encoding: gzip' \
+  --data-binary @<(printf '%s' "${payload_gzip}" | gzip -c) \
+  "${UPLOAD_URL}")"
+echo "gzip upload HTTP ${gzip_upload_code}"
+cat /tmp/graph_upload_gzip_resp.json
+echo
+
+if [[ "${gzip_upload_code}" != "200" ]]; then
+  echo "FAIL: gzip upload expected 200" >&2
   exit 1
 fi
 if [[ "${graphs_code}" != "200" ]]; then