Default text-based progress sink used by non-GUI installs. Writes
status and log lines to stderr; renders an in-place progress bar when
stderr is a TTY, otherwise emits no progress lines.
Verify the compressed-payload SHA-256 emitted by the build tool. blobs
is a flat list of the unique embedded byte slices (one per deduplicated
storage file, in D_* declaration order); uninstaller_data is the
embedded uninstaller (empty slice for an uninstaller binary). Call at
process start — the generated main() invokes it before anything else.