* fix(nginx): defer cors to gateway allowlist
Remove proxy-level wildcard CORS handling so browser origins are controlled by the Gateway allowlist and stay aligned with CSRF origin checks.
* docs: document gateway cors allowlist
Clarify that same-origin nginx access needs no CORS headers while split-origin or port-forwarded browser clients must opt in with GATEWAY_CORS_ORIGINS.
* docs(gateway): record cors source of truth
Document that Gateway CORSMiddleware and CSRFMiddleware share GATEWAY_CORS_ORIGINS as the split-origin source of truth.
* fix(gateway): align cors origin normalization
* docs: clarify gateway langgraph routing
* docs(gateway): update runtime routing note
- Updated documentation and comments to reflect the transition from LangGraph Server to Gateway.
- Changed default URLs in ChannelManager and tests to point to Gateway.
- Removed references to LangGraph Server in deployment scripts and configurations.
- Updated Nginx configuration to route API traffic to Gateway.
- Adjusted frontend configurations to utilize Gateway's API.
- Removed LangGraph service from Docker Compose files, consolidating services under Gateway.
- Added regression tests to ensure Gateway integration works as expected.
Co-authored-by: Copilot <copilot@github.com>