Fix getHexagonRequiredNodeId1 case 3 condition for all even rings

[Copilot]

ShapeGenerator::getHexagonRequiredNodeId1 side 4 (case 3) duplicates the 3rd entry only for even-k rings, but the condition was hardcoded to k == 4 instead of checking all even rings.

• Changed condition from k == 4 && pos == 2 to (k % 2 == 0) && pos == 2

// Before
if (k == 4 && pos == 2) {
    return s + 3 * k - 1;
}

// After
if ((k % 2 == 0) && pos == 2) {
    return s + 3 * k - 1;
}

Verified against the full expected sequence (127 values through ring 7) and the generateHexagon_61cells_withSeparation integration test.