Function is_safe_ident 

pub fn is_safe_ident(name: &str) -> bool

True if name is a safe SQL identifier candidate (alphanumeric + underscore, non-empty, does not start with a digit). Loosely the same predicate as is_safe_unquoted minus the case sensitivity and reserved-word check — kept as a separate helper because it’s a generic “could this be a safe identifier” question used by filename validation.