Add support for fade transitions for music segments

[Kolfering]

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The best way to fix this problem is to explicitly handle conversion from lua_tonumber to integer, clarifying the intended behaviour. The code should explicitly round, floor, ceil, or truncate as appropriate, and check that the value is within the allowed range for uint32_t (i.e., >= 0 and <= UINT32_MAX), giving an error if the value is invalid.

The recommended fix is to:

• Retrieve the value from lua_tonumber(L, 2) into a lua_Number variable.
• Check that the value is integral (e.g., that it matches its uint32_t representation, or that it equals floor(val)).
• Check that the value is within the range for uint32_t (0 ≤ val ≤ UINT32_MAX).
• If checks pass, cast to uint32_t (using static_cast<uint32_t>(val)).
• If invalid, return a Lua error.

You may need to #include <cmath> for floor or similar, and possibly #include <limits> for UINT32_MAX.

All changes should be made only in the code snippets shown, specifically in the implementation of Lua_MusicPreset_Add_Segment around line 325.

The best way to fix this problem is to remove the unused variable from the unpacking/destructuring assignment on line 368 in Source_Files/Lua/lua_music.cpp. Specifically, change the line

auto [music_index, preset_index, segment_index] = Get_MusicSegment(index);

to

auto [music_index, preset_index, /*segment_index*/] = Get_MusicSegment(index);

or, preferably, omit it entirely via C++17's structured binding and the ignore-diskards:

In C++, if you are using structured bindings and don't need one of the unpacked values, you can simply ignore it, like so:

auto [music_index, preset_index, std::ignore] = Get_MusicSegment(index);

But C++17 does not actually support std::ignore for structured bindings; it's usually used only for std::tuple::tie(). Therefore, the standard way is just to declare only the variables you need. Since the current code returns a std::tuple<uint32_t, uint32_t, uint32_t>, and structured bindings force you to bind all three values, a workaround is to retrieve the tuple into a named variable, and then unpack only the necessary elements, or to keep the unused variable but name it _ to indicate that it's intentionally unused.

But to keep things clean, it's best just to bind the variables you actually use, or assign the unused value to a variable named _ as per common convention.

Modification required:

• On line 368, change auto [music_index, preset_index, segment_index] = ... to auto [music_index, preset_index, _] = ... or, if your team does not use _ for unused variables, simply revert to using a std::tuple and access only the first two indices.

But as per convention and for clarity, replacing segment_index with _ will suffice.

No other changes or new imports/methods are required.