Function reverse_sign 

pub const fn reverse_sign(grade: usize) -> i8

Sign factor for the reverse of a k-blade.

The reverse operation flips the order of basis vectors in a blade, introducing a sign of (-1)^(k(k-1)/2) where k is the grade.

The pattern is: ++--++--... (repeating every 4 grades)

Grade	k(k-1)/2	Sign
0	0	+1
1	0	+1
2	1	-1
3	3	-1
4	6	+1
5	10	+1
6	15	-1
7	21	-1

Example

use clifford_codegen::algebra::reverse_sign;

assert_eq!(reverse_sign(0), 1);  // scalar: +
assert_eq!(reverse_sign(1), 1);  // vector: +
assert_eq!(reverse_sign(2), -1); // bivector: -
assert_eq!(reverse_sign(3), -1); // trivector: -
assert_eq!(reverse_sign(4), 1);  // 4-vector: +