Function resolve_address_book_input 

pub fn resolve_address_book_input(
    input: &str,
    config: &Config,
) -> Result<Option<(String, String)>, ScopeError>

Resolves a user-supplied input string against the address book.

Label lookup (requires @ prefix): If the input starts with @, the remainder is looked up as a label. Example: @main-wallet resolves to the address with label “main-wallet”. This convention distinguishes label lookups from raw addresses.

Address match (no @): If the input does not start with @, only direct address matching is attempted (to inject chain info from the address book). Raw addresses and token identifiers are not treated as labels.

Returns Ok(Some((address, chain))) when resolved, Ok(None) when no @ prefix and no address match, or Err when the @ prefix was used but the label wasn’t found.