getFinalizedHead
Get the hash of the latest finalized block.
Standard Substrate RPC: chain_getFinalizedHead. Returns a 32-byte block hash as 64-char hex (without 0x prefix).
Used as a tip fingerprint for cache validity: if the finalized head hasn't changed since last sync, dust state is guaranteed current.
Return
Block hash (64 hex chars)
Throws
if network connectivity fails
if request times out
if node returns JSON-RPC error