v0.8.0

🏛️ Arch Linux support

• Phoenix now installs on Arch and its derivatives — Manjaro, EndeavourOS,
  Garuda, CachyOS, ArcoLinux, Artix (and anything with ID_LIKE=arch, e.g.
  SteamOS) — on x86_64 / aarch64. detect_os gains a fourth target and the
  installer dispatches to a pacman path; phoenix-term doctor and preflight
  grew Arch arms too.
• Everything comes from the official repos, Ghostty included (extra/ghostty)
  — no COPR or .deb dance. The one exception, lazyssh (AUR-only), is fetched
  from its GitHub release like on the other distros.
• ⚠️ Full system upgrade on install. Arch forbids partial upgrades, so the
  installer runs a complete pacman -Syu rather than -Sy <pkg> — it upgrades
  your whole system, not just Phoenix's packages (a kernel bump may want a
  reboot). This is the safe, Arch-correct behavior.
• RHEL/Rocky/Alma remain unsupported — they're rejected explicitly, same as
  before.