Share the base++zim++trailer assembly behind a small helper, then add two bundle
builders on top: BuildApp writes a macOS .app (Info.plist, the viewer under
Contents/MacOS, an .icns in Resources), and BuildAppDir writes an AppImage-style
.AppDir (AppRun, a Terminal=false .desktop launcher, a PNG icon). Both keep the
trailer at the tail so Embedded still finds the archive at runtime.
BuildZIM walks a cloned host directory, turns every file into a content
entry with a MIME inferred from its extension, picks a main page, and adds
the standard metadata plus a mainPage redirect. state.json is skipped.
BuildBinary appends the archive to a copy of kage behind a KAGEPCK1 trailer,
and Embedded detects that trailer at startup so the binary serves itself.
Handler maps / to the main page and /path to a content entry, the same
handler the embedded viewer uses.
Duc-Tam Nguyen