amiberry-packaging-install

Reference workflow for Amiberry packaging, install-layout, and runtime-path fixes. Use for distro packaging changes, `BUNDLE_SDL`, RPATH and shared-library bundling work, DEB or RPM dependency adjustments, CI matrix packaging toggles, Windows portable install detection, and executable-directory vs current-working-directory path bugs in files such as `cmake/linux/install.cmake`, `packaging/CMakeLists.txt`, `.github/workflows/c-cpp.yml`, and `src/osdep/amiberry.cpp`.