Revert "Fix Zig cache races in remote build scripts"

SWARM-112: bump Android targetSdkVersion 34 -> 35

artifacts: publish sleek-host Linux x86_64 build (sif-egl-fix)

sif: fix EGL/GL vendor discovery inside apptainer/singularity container

Cursor: Apply local changes for cloud agent

Cursor: Apply local changes for cloud agent

Cursor: Apply local changes for cloud agent

Cursor: Apply local changes for cloud agent

Simplify .boxci to merge-only; issue→patch is builtin to boxci.

Add Buildkite pipeline for check and optional nixbuild APK/Flatpak artifacts.

Shrink desktop Nix closure and keep Cachix hits stable.