- the packager resources only carried assets/i18n, so installed builds
showed blank toolbar glyphs: add assets/icons to the Windows/macOS
packages and install it to /usr/share/oak/icons in the deb/rpm/pkg
scripts;
- icon_path resolved through the compile-time CARGO_MANIFEST_DIR (the CI
checkout path), which never exists on a user machine: search the
runtime layouts instead — dev checkout, next to the executable,
Contents/Resources, usr/lib/oak-editor (cargo-packager's deb/AppImage
layout) and /usr/share/oak — mirroring the i18n pack search, which
gains the same usr/lib/oak-editor candidate so the AppImage finds its
language packs too.
Verified: oak-app 556 tests pass; the deb and rpm now carry
/usr/share/oak/icons/{dark,light}/*.png.