Function count_relationships_by_relation 

pub fn count_relationships_by_relation(
    conn: &Connection,
    namespace: &str,
    relation: &str,
) -> Result<usize, AppError>

Counts relationships matching the given relation type within a namespace.

Used by prune-relations --dry-run to preview the number of relationships that would be deleted without actually modifying the database.

Errors

Returns Err(AppError::Database) on any rusqlite failure.