pub fn validate_shard_header(path: &Path) -> Result<(), ShardError>Expand description
Validate that a shard file starts with the expected header line.
Reads only the first line and checks it matches [SHARD_HEADER].
Empty files or files starting with the correct header pass.
Forwarding-pointer shards are silently accepted (legacy compat).
§Errors
Returns ShardError::CorruptedShard if the first line doesn’t match,
or ShardError::Io if the file can’t be read.