Skip steps whose dist/ artifact already exists; add --clean/-c to
force a full rebuild. Install sphinx/linuxdoc, build, pyinstaller
in their respective steps instead of upfront. Auto-add flathub
remote and install missing Flatpak SDK/runtime deps before step 4.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Collects all four artifacts under <repo>/dist/ (PyInstaller and Flatpak
renamed to testium-<version>(.suff); wheel and AppImage keep PEP 427 /
appimage-builder original names). Re-uses scripts/build_env.sh and
set_env.sh, same venv as run.sh. AppImage build.sh now picks the actual
output file dynamically instead of a hardcoded lowercase name.