fix(rpc): emit canonical block hash in newHeads subscription

[puneet2019]

Description

eth_subscribe("newHeads") publishes the derived Ethereum-header hash (keccak(RLP(eth header))), but eth_getBlockByNumber / eth_getBlockByHash report and resolve by the CometBFT block hash (RPCMarshalHeader sets "hash" to it; GetBlockByHash looks it up via CometBFT). So a newHeads notification's hash doesn't match the same block from eth_getBlockByNumber, and passing it to eth_getBlockByHash / eth_getLogs({blockHash}) returns "block not found".

This completes #725 — that PR aligned the JSON-RPC responses and added the canonical hash to the stream header (stream.RPCHeader.Hash = data.BlockID.Hash), but the WebSocket subscribeNewHeads handler was left emitting header.EthHeader.

Change (rpc/websockets.go):

- Result: header.EthHeader,
+ Result: rpctypes.RPCMarshalHeader(header.EthHeader, header.Hash.Bytes()),

RPCMarshalHeader returns the full header map with the canonical "hash", so newHeads now matches eth_getBlockByNumber.

How to review / test

newHeads.hash now equals eth_getBlockByNumber(<same height>).hash, and that hash resolves via eth_getBlockByHash / eth_getLogs({blockHash}) (previously "block not found"). Verified end-to-end in a downstream chain adopting cosmos/evm/rpc (WS eth_subscribe e2e green). Happy to add an integration assertion if preferred.

Author Checklist

• targeted the main branch
• left instructions on how to review the changes
• follow-up completing fix: inconsistent block hash in json-rpc responses #725 (no separate issue)

🤖 Generated with Claude Code

[greptile-apps]

PR author is not in the allowed authors list.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 66.99%. Comparing base (7c492af) to head (f7760bb).

Files with missing lines	Patch %	Lines
rpc/websockets.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1214      +/-   ##
==========================================
- Coverage   67.02%   66.99%   -0.03%     
==========================================
  Files         320      320              
  Lines       23438    23438              
==========================================
- Hits        15709    15702       -7     
- Misses       6572     6578       +6     
- Partials     1157     1158       +1     

Files with missing lines	Coverage Δ
rpc/websockets.go	16.42% <0.00%> (ø)

... and 1 file with indirect coverage changes

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