Missing hash field in block header response when using useRcBlock=true

[eugypalu]

Description

When calling /blocks/head/header?useRcBlock=true or /blocks/{blockId}/header?useRcBlock=true, the response is missing the hash field for the Asset Hub block.

Expected vs. Actual Behavior

The response should include the hash field of the Asset Hub block, consistent with the standard header response format and other endpoints that use useRcBlock=true.

Actual behavior:
The response includes:

parentHash
number
stateRoot
extrinsicsRoot
digest
rcBlockHash
rcBlockNumber 
ahTimestamp

But it's missing:
hash