As a developer, I want the MCP Gateway to support streaming/SSE-based tools, so that streaming tools (i.e. a long running tool) continues to function through the gateway.

Considerations:

• This will probably require keeping connection open to backend(s) as needed.
• See https://github.com/david-martin/mcp-helper/issues/3 for more info on the flow of requests for a client to set up the stream
• Assess and document risk of memory/cpu pressure from long-lived streams
• Evaluate fan-out strategy for multi-backend scenarios (e.g., duplicate requests, selective routing)
• Gate behind feature flag or config toggle for MVP, given concerns on architecture & scaling

https://github.com/kagenti/mcp-gateway/issues/24