Function shard_of_bytes 

pub fn shard_of_bytes(raw: &[u8], num_shards: u32) -> Option<u32>

Determines the shard ID from raw address bytes (simpler version).

This is a simpler alternative to shard_of_address_bytes that uses a direct last-byte approach instead of the full mask-based algorithm.

Arguments

• raw - Raw address bytes
• num_shards - The total number of shards in the network

Returns

• Some(0xFF) for metachain addresses (last byte == 0xFF)
• Some(shard_id) for regular shards
• None if the address is empty