fix(casper): caip2 worked example points at unreachable RPC endpoints

[okwme]

Both RPC endpoints in the casper CAIP-2 profile are unreachable, so the worked example cannot be run as written:

http://34.224.191.55:7777/rpc   (listed as Casper Mainnet)  -> timeout
http://52.35.59.254:7777/rpc    (listed as Testnet)         -> timeout

Replaced with the Casper Association's current hostnames, verified 2026-09-14 to return exactly the values this profile documents:

$ curl -s -X POST https://node.mainnet.casper.network/rpc -H "Content-Type: application/json" \
    -d "{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"info_get_status\",\"params\":{}}" | jq -r .result.chainspec_name
casper

$ curl -s -X POST https://node.testnet.casper.network/rpc ... | jq -r .result.chainspec_name
casper-test

Using hostnames rather than bare IP addresses should also survive the next infrastructure change.

Found while writing a CAIP-19 asset profile for this namespace, as part of FAR, an open cross-reference between CAIP-19, CoinGecko and ISO 24165 identifiers.