A dry run never prompts, but plain `hermes uninstall --dry-run` still went
through the interactive-terminal gate and was refused when stdin was not a
TTY. Exempt --dry-run from that gate, matching --gui and --data.
The GUI removal plan also omitted desktop-installed-apps.json, which
uninstall_gui() deletes. List it under "Will remove" so the preview matches
what a real run removes.
Adds a CLI-level regression test covering `--gui --dry-run` with and
without --yes, and plain `uninstall --dry-run`, asserting nothing is
prompted or removed.
Refs: #128974
Salvaged-from: #131147
2eadea653a