sony-headphones-client: switch to maintained fork

[griffi-gh]

sony-headphones-client is currently built from Plutoberth/SonyHeadphonesClient which has been archived since July 2025.
Meanwhile, mos9527/SonyHeadphonesClient seems to be the most actively maintained fork which also implements support for XM5/XM6 series.

The only issue with the mos9527 fork is that at the moment it currently:

• does not offer any stable releases for the v2 branch, so would need to be pinned against master.
• the reworked master/v2 branch currently doesnt support older XM3/XM4 headphones properly, so the upgrade would cause regression for users of those

[depeo]

I was happy to see that there is an app for my Sony headphones, and I tried to getting a local derivation working, but I wasn't able to, it seems like the upstream has pinned an old version of imgui, I kept getting errors like this:

/build/source/client/Client.cpp:1392:61: error: 'struct ImGuiStyle' has no member named 'FontSizeBase'
It would be great to see a working derivation in nixpkgs.

[NicoWeio]

Re 1: Have you asked / is there an ongoing discussion about stable releases?
Re 2: Using an XM3 myself, I biasedly assume that a large fraction of users still has the XM3/4, so I'd rather wait until all versions are supported in a single codebase – if it's only a matter of weeks – or see if we can work around this by facilitating overrides, creating another package, …