Add checklist item 10 and full detail section for the rapidapi-proxy-secret
Kubernetes secret that must be created in each API namespace (zip-enrichment,
holidays, air-quality) before the Phase 3 server middleware can validate
incoming RapidAPI requests.
Includes:
- Checklist item 10 in the summary list
- Full detail section with kubectl commands for all 3 namespaces
- Note about placeholder ExternalSecret manifests and ESO (issue #61)
- Updated dependency-order diagram
Closesleeworks-agents/api-company#60