Mercury server directory from Nostr events

[tomt1664]

Add to main page webpage that gets all 'mercurylayer' server advertisement events advertising the specific service from a relay and then lists them.

e.g.

WebSocket Connection:

Connects to a Nostr relay using its WebSocket URL.
Subscription to Events:

Sends a REQ (request) message to subscribe to events with a specific tag.
Filters events by kind and tags (#service with the value relay-hosting in this example).
Event Handling:

When the relay sends matching events, they are displayed on the webpage dynamically.
Event Display:

Extracts the pubkey, content, and tags from each event and adds them to the webpage.