fix(show): star marker, aligned gutter and smarter AUR merge

N?? / show marks the upstream candidate with "*" instead of ">" (the
prompt, which read as a command in logs), and every line but the note
gets a two-character gutter: "  " for the installed record, "* " for the
candidate, so keys and colons line up. The plain native fallback (zypper,
unmergeable records) and the not-installed candidate use the same gutter.

pacman records (-Qi with -Si or the AUR helper's -Sia) are now compared
the way they are meant:
- values unwrapped (continuation lines joined, runs of blanks as one):
  yay wraps Depends On / Optional Deps at 80 columns even without a
  terminal unless COLUMNS=0, which the helper now gets for -Qua and -Sia
- Depends On, Provides, Conflicts With, Make/Check Deps and the other
  lists as sets of exact tokens in any order (a constraint is a change)
- Optional Deps by package names ("name: description [installed]" in
  -Qi, bare names from the AUR)
- a differing value is one line like -Qi, Optional Deps one entry per
  line; candidate-only fields sit next to their counterpart (Repository
  after Version, AUR URL after URL, Maintainer after Packager, ...)

Verified on recorded claude-desktop records (paru 2.1.0, yay 13.0.1, the
installed 2.9939.4-1 from the AUR's own .SRCINFO); discovery/pacman.md
section 15.2.

tests/unit/data/aur/Sia-paru-claude-desktop.txt

@@ -0,0 +1,21 @@
+Repository      : aur
+Name            : claude-desktop
+Version         : 2.31226.1-1
+Description     : Official Claude AI desktop app from Anthropic — Chat, Cowork, and Claude Code
+URL             : https://claude.com/download
+AUR URL         : https://aur.archlinux.org/packages/claude-desktop
+Groups          : None
+Licenses        : LicenseRef-Proprietary
+Provides        : None
+Depends On      : alsa-lib  at-spi2-core  bubblewrap  cairo  dbus  expat  gcc-libs  glib2  glibc  gtk3  hicolor-icon-theme  libcap-ng  libcups  libdrm  libnotify  libpipewire  libseccomp  libsecret  libx11  libxcb  libxcomposite  libxdamage  libxext  libxfixes  libxkbcommon  libxrandr  libxtst  mesa  nspr  nss  pango  socat  systemd-libs  util-linux-libs  virtiofsd  xdg-desktop-portal  xdg-utils  qemu-system-x86  edk2-ovmf
+Make Deps       : None
+Check Deps      : None
+Optional Deps   : gnome-keyring  kwallet  libayatana-appindicator  xdg-desktop-portal-gtk  xdg-desktop-portal-kde  qemu-system-aarch64  edk2-aarch64
+Conflicts With  : claude  claude-desktop-bin
+Maintainer      : diazkev314
+Votes           : 21
+Popularity      : 6.45849
+First Submitted : Sun, 5 Jul 2026 01:58:02
+Last Modified   : Fri, 9 Oct 2026 23:31:19
+Out Of Date     : No
+