xceadmin's custom_target only built+tested (stamp-file output, no
install:true) — nix build .#xcecore succeeded but shipped nothing in
result/bin, unlike every other component.
Add meson.add_install_script('meson-install.sh'): copies the
xceadmin/xcecommon package dirs (not the whole build-dir venv, whose
pip-generated shebang hardcodes a build path that stops existing after
the build) into $out/lib/xceadmin-site, then writes a wrapper at
$out/bin/xceadmin whose shebang and PYTHONPATH are resolved against
the install script's own nix build environment — real /nix/store
paths for python3 and each dependency (pycapnp, pyyaml, jsonschema,
click), so nix's reference scanner keeps them alive in the closure.
No venv activation needed at runtime.
Verified: meson install --destdir and nix build --option sandbox
false .#xcecore both produce a working result/bin/xceadmin, runnable
standalone with a stripped-down PATH-only environment.
Rongsong Shen
893a01db7b