fix(install): apply gh-r libc preference after CPU narrowing

The previous fix excluded musl assets in the OS-pattern stage, which
runs before the CPU filter. Repos that ship their x86_64 Linux build
only as musl while providing non-musl builds solely for ARM (dua-cli,
git-absorb, mcfly, navi, ripgrep, tre, xh, zoxide) ended up with a
wrong-architecture asset or none at all.

Make the Linux OS pattern libc-neutral and emit the detected host libc
as a fourth field from .zi::get-architecture. The narrowing loop now
uses the libc token as its lowest-priority filter, and an explicit
post-CPU step drops musl assets on glibc hosts (or requires them on
musl hosts) only when alternatives survive, so a musl-only architecture
still resolves.

Full tests/gh-r.zunit suite: 151 passed, 0 failed, 7 skipped. tokei
selects -linux-gnu (ships both variants), bicep selects bicep-linux-x64,
musl-only tools select their musl asset; Alpine hosts verified to
prefer musl with intact fallback.

Signed-off-by: Vladislav Doster <mvdoster@gmail.com>

zinit-install.zsh

@@ -1408,12 +1408,8 @@ builtin source "${ZINIT[BIN_DIR]}/zinit-side.zsh" || {
       fi
       ;;
     (Linux)
+      _sys='linux'
       [[ $OSTYPE == *musl* || "$(command ldd --version 2>&1)" == *musl* ]] && _clib="musl"
-      if [[ $_clib == musl ]]; then
-        _sys='musl*~^*linux*'
-      else
-        _sys='linux*~*musl'
-      fi
       ;;
     (MINGW* | MSYS* | CYGWIN* | Windows_NT)
       _sys='pc-windows-gnu'
@@ -1439,7 +1435,7 @@ builtin source "${ZINIT[BIN_DIR]}/zinit-side.zsh" || {
       +zi-log "{e} {b}gh-r{rst}Unsupported CPU: {obj}$_cpu{rst}"
       ;;
   esac
-  echo "${_sys};${_cpu};${_os}"
+  echo "${_sys};${_cpu};${_os};${_clib}"
 } # ]]]
 # FUNCTION: .zinit-get-latest-gh-r-url-part [[[
 # Gets version string of latest release of given Github
@@ -1507,6 +1503,17 @@ builtin source "${ZINIT[BIN_DIR]}/zinit-side.zsh" || {
       fi
     done
 
+    # A musl asset is correct only when the host libc is musl — but runs after
+    # the CPU filter so a musl-only arch (e.g. only x86_64 build is musl) still resolves.
+    if (( $#list > 1 )); then
+      if [[ $parts[4] == musl ]]; then
+        filtered=( ${(M)list[@]:#(#i)*musl*} )
+      else
+        filtered=( ${list[@]:#(#i)*musl*} )
+      fi
+      (( $#filtered > 0 )) && list=( ${filtered[@]} )
+    fi
+
     if (( $#list > 1 )) { filtered=( ${list[@]:#(#i)*.(sha[[:digit:]]#|asc)} ) && (( $#filtered > 0 )) && list=( ${filtered[@]} ); }
 
     if (( !$#list )); then