Opens an EventSource on this app's /sse/clock route, which streams a
tick every second to everyone subscribed and a subscribers count whenever someone joins
or leaves. Loaded direct-connect this tests the adaptor's streaming responses; loaded through the front-end proxy it
tests the proxy passing an open-ended response through — same page either way. Open it in two tabs and close one:
the count drops, which is the server noticing the client go away.
Connection: connecting… Subscribers: –