Add haneul namespace and CAIP-2 spec

[GeunhwaJeong]

This PR adds documentation for the Haneul blockchain platform and a corresponding CAIP-2 specification which will unlock cross-chain integrations with Haneul.

[GeunhwaJeong]

Testnet RPC Endpoint

URL: http://51.75.242.118:9000

1. Chain Identifier Verification (CAIP-2)

curl -s -X POST http://51.75.242.118:9000 \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"haneul_getChainIdentifier","params":[]}'

Expected response:

{"jsonrpc":"2.0","id":1,"result":"afd5afb7"}

2. Network Activity Verification

curl -s -X POST http://51.75.242.118:9000 \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"haneul_getLatestCheckpointSequenceNumber","params":[]}'

Expected response (checkpoint number will increase over time):

{"jsonrpc":"2.0","id":1,"result":"2603412"}

[bumblefudge]

it might be worth mentioning (even though it's not strictly pertinent to chain identifiers) what guarantees do and don't break on a "reset". is all chainstate just gone and set to 0, leaving only addresses but no balances or state or data? or is some state/data persisted across resets?

[bumblefudge]

if there are syntactic limits (like, no future network name will be longer than X ASCII characters/codepoints) , or how to validate the genesis hash you get back (how many bytes? how base-encoded to ASCII?), I would add them to this section

[bumblefudge]

I would probably add, either here or adding a ### Governance section, who and how future network identifiers are decided (and who and how chain resets are decided).

[bumblefudge]

I think this could be merged as-is because it's a pretty straight-forward chainId system, but the clarifying questions I left would all be worth answering if they can be dispensed by adding a sentence and/or a link each! I recommend doing so because these profiles serve as a kind of onboarding resource for devs new the space, and avoid cross-chain footguns firing off because of faulty assumptions about the underlying semantics or mechanics of network identification/resolution systems.

[GeunhwaJeong]

Hi @bumblefudge, thanks for the review! I've pushed an update addressing your feedback.