fix(sui): caip2 resolution example uses JSON-RPC, deprecated on public fullnodes

[okwme]

The sui CAIP-2 profile resolves the chain identifier with suix_getChainIdentifier. Sui has deprecated JSON-RPC on public fullnodes, so that example no longer runs:

$ curl -s -X POST https://fullnode.mainnet.sui.io:443 -H "Content-Type: application/json" \
    -d "{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"suix_getChainIdentifier\",\"params\":[]}"
{"jsonrpc":"2.0","error":{"code":-32601,"message":"Method not found. JSON-RPC on public
 fullnodes has been deprecated. Please migrate to gRPC or GraphQL endpoints. ..."}}

Unlike a simple method rename, no JSON-RPC method works — the transport itself is gone — so the example cannot be repaired in place.

Replaced with the GraphQL equivalent, verified on 2026-09-14:

$ curl -s -X POST https://graphql.mainnet.sui.io/graphql -H "Content-Type: application/json" \
    -d "{\"query\":\"{ chainIdentifier }\"}"
{"data":{"chainIdentifier":"4btiuiMPvEENsttpZC7CZ53DruC3MAgfznDbASZ7DR6S"}}

One substantive difference, now documented in the profile. The GraphQL field returns the full genesis checkpoint digest in base58, whereas the old JSON-RPC method returned the four-byte prefix directly. That value base58-decodes to the 32 bytes 35834a8ac17ca48fb14ac8f99c17c98747e95dd07294ae41a46b382246a4499b, whose first four bytes are 35834a8a — exactly the mainnet reference this profile already documents. The derivation is spelled out so an implementer is not left to infer it.

This also removes a trailing sentence stating that the response returns the first four bytes, which was true of the JSON-RPC reply but is not true of the GraphQL field.

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. The iota profile has a closely related issue (#210), since it was derived from this one.