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/fakes/paru/paru

@@ -11,8 +11,9 @@
 # noise (yay's colored root warning on stdout), none (nothing to upgrade: exit 1, no output) or
 # fail (the AUR is unreachable: exit 1 with the recorded error). Packages purged by the fake pacman
 # are not listed. -Sia PKG prints data/aur/Sia-<helper>-PKG.txt (else the helper's not-found
-# error, exit 1), twice with FAKE_AUR_SIA=twice (a record that cannot be merged); -Sua exits
-# FAKE_AUR_SUA_RC (default 0).
+# error, exit 1), twice with FAKE_AUR_SIA=twice (a record that cannot be merged), or the variant
+# Sia-<helper>-PKG-<FAKE_AUR_SIA>.txt when it exists; -Sua exits FAKE_AUR_SUA_RC (default 0).
+# claude-desktop: yay's record is the wrapped one yay prints without COLUMNS=0, recorded verbatim.
 # shellcheck source=../fakelib.bash
 . "${BASH_SOURCE[0]%/*}/../fakelib.bash"
 fake_log "$@"
@@ -38,6 +39,10 @@ case ${1:-} in
 	printf '%s\n' "$out"
 	;;
 -Sia)
+	if [[ -n ${FAKE_AUR_SIA:-} && -f $D/Sia-$FAKE_NAME-${2:-}-$FAKE_AUR_SIA.txt ]]; then
+		cat "$D/Sia-$FAKE_NAME-$2-$FAKE_AUR_SIA.txt"
+		exit 0
+	fi
 	if [[ -f $D/Sia-$FAKE_NAME-${2:-}.txt ]]; then
 		cat "$D/Sia-$FAKE_NAME-$2.txt"
 		[[ ${FAKE_AUR_SIA:-} != twice ]] || cat "$D/Sia-$FAKE_NAME-$2.txt"