perf(int256): Optimize int256 Pacakge

[notJoon]

Summary

This PR optimizes the int256 package by removing unused functions and improving initialization performance.

Changes

• Remove 25+ unused arithmetic and utility functions that are not used in this codebase
• Optimize MaxInt256 and MinInt256 initialization using direct word arrays instead of decimal parsing
• Avoid unnecessary SetInt64 calls when creating new Int256 arrays
• Update gas measurement tests to reflect the optimizations

Removed Functions

The following functions were removed as they are not used in any contract:

• AddUint256, SubUint256, MulUint256, DivUint256
• AddDelta, AddDeltaOverflow
• Quo, Rem, Mod
• And (bitwise operation)
• Neq, Lte, Gte (comparison operations)
• SetUint64, SetUint256
• NegOverflow, AbsGt, AbsLt, AbsOverflow
• And several others...

[jinoosss]

There is a structural issue with Int256 package operations.
When overflow occurs, the value is set to the minimum or maximum value of uint256, not the minimum or maximum value of int256.

As this is a structural issue, thorough discussion will likely be necessary.

func (z *Int) Add(x, y *Int) *Int {
	z = z.initiateAbs()

	if x.neg == y.neg {
		// If both numbers have the same sign, add their absolute values
		z.abs.Add(x.abs, y.abs)
		z.neg = x.neg
	} else {
		// If signs are different, subtract the smaller absolute value from the larger
		if x.abs.Cmp(y.abs) >= 0 {
			z.abs.Sub(x.abs, y.abs)
			z.neg = x.neg
		} else {
			z.abs.Sub(y.abs, x.abs)
			z.neg = y.neg
		}
	}

	// Ensure zero is always positive
	if z.abs.IsZero() {
		z.neg = false
	}

	return z
}

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[notJoon]

replaced by #1021