Replaces the generated dagger scaffold with a real BuildLinux function
that compiles swap-watchdog, force-quit-gui, and kdotool (not packaged
for Fedora, so built from source via cargo) inside an ephemeral
nixos/nix container -- no gtk3-devel/dbus-devel/rust toolchain needs
installing on the host. The host's own Go toolchain is mounted in so
the build matches go.mod's required version exactly.
Nix's glibc uses a non-FHS dynamic linker path that doesn't exist
outside the container, so the built binaries are patched with
patchelf to point at the host's real ld.so; the stale nix-store
RUNPATH entries are harmless since ld.so just skips nonexistent
directories and falls through to the host's normal library search
path, where the real libgtk-3/libdbus-1/etc already live.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
