`GET /v1/ws` — upgrade to a WebSocket carrying the live peg-state stream.
Not a JSON endpoint: a successful handshake returns 101 Switching Protocols. After upgrade the server pushes {op:"update", ...} and
{op:"heartbeat", ts} frames; the client may send {op:"ping"} (→ pong)
and {op:"subscribe"|"unsubscribe", assets:[...]}. Browsers must present an
allowlisted Origin; server-to-server tools may omit it.
GET
`GET /v1/ws` — upgrade to a WebSocket carrying the live peg-state stream.
Response
Switching Protocols — WebSocket established
`GET /v1/ws` — upgrade to a WebSocket carrying the live peg-state stream.