ISseService.open(ctx: IRequestContext): ISseConnection
Opens a new SSE connection for the given request context.
Constructs a ReadableStream, captures its controller, sets the SSE
response headers on the context's response builder, calls
ctx.response.stream(rs) to obtain the HandlerResult, and returns a
connection the handler can use to send messages after the handler returns.
ctx: IRequestContext
The current request context
The SSE connection with its result