64-bit width LogicValues can be incorrect if their integer value is larger than the maximum positive int value in Dart

[mkorbel1]

Describe the bug

Doing things like grabbing a 64-bit slice of a _BigLogicValue or constructing a LogicValue using ofBigInt with width 64 with a value that could be interpreted as a negative signed int can cause clamping behavior in BigInt.toInt(). This causes wrong operation results in a number of cases.

To Reproduce

One example that reproduces the issue (this fails):

      final extraWide = LogicValue.ofBigInt(
        BigInt.parse('f' * 16 + 'f0' * 8, radix: 16),
        128,
      );
      final smaller = extraWide.getRange(0, 64);
      expect(smaller.toInt(), equals(0xf0f0f0f0f0f0f0f0));

Expected behavior

Large 64-bit int values are treated as unsigned during conversions

Actual behavior

Sometimes int values are treated as signed and clamped

Additional: Dart SDK info

No response

Additional: pubspec.yaml

No response

Additional: Context

This type of behavior could occur in a number of places, so it's important to consider everywhere it might occur.