Fix AttributedScopeStack equality type check

[Copilot]

AttributedScopeStack.Equals was rejecting comparisons with other AttributedScopeStack instances, so equality always returned false and could throw on unrelated types. This change restores correct type checking and adds focused equality coverage.

• Equality fix

  • Correct the null/type guard so AttributedScopeStack comparisons proceed.

• Tests

  • Add NUnit coverage for equal/unequal stacks, null, and different-type inputs.

public override bool Equals(object other)
{
    if (other == null || !(other is AttributedScopeStack))
        return false;

    return Equals(this, (AttributedScopeStack)other);
}

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Incorrect logic in AttributedScopeStack.Equals() method</issue_title>
<issue_description>The Equals(object other) override in AttributedScopeStack contains a logic error that causes it to always return false when comparing two AttributedScopeStack instances, breaking equality comparison.

Current Behavior

public override bool Equals(object other)
{
    if (other == null || (other is AttributedScopeStack))
        return false;
    return Equals(this, (AttributedScopeStack)other);
}

Returns false when other is an AttributedScopeStack (incorrect)
Would attempt to cast and compare when other is not an AttributedScopeStack, causing InvalidCastException

Expected Behavior
The method should return false when other is null or not an AttributedScopeStack, and perform equality comparison when it is.
Proposed Fix

public override bool Equals(object other)
{
    if (other == null || !(other is AttributedScopeStack))
        return false;
    return Equals(this, (AttributedScopeStack)other);
}
```</issue_description>

<agent_instructions>Add a unit test if possible for it</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes Incorrect logic in AttributedScopeStack.Equals() method #110

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[danipen]

LGTM