skip radicale and officer-caldav on a macOS dev install, not the platform

Hit live: `brew install radicale` fails outright, "No available formula with the name
radicale" — it is a pure-Python package (pip/pipx), not something Homebrew carries, unlike
every other name in that list. apt/pacman/dnf all package it for real and are untouched.

Narrower than removing the feature: officer-caldav (Calendar/Contacts) stays CORE on Linux.
On macOS the sidecar has nowhere to find Radicale — resolveRadicale() failing is exactly the
"took a whole sidecar down on a fresh install" case its own test already guards against — so
CORE_PROCESSES leaves it out on Darwin rather than let it crash-loop. Calendar/Contacts is
the one core feature not available on a Mac dev install; nothing else changes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/setup/machine-setup/lib/packages.sh

@@ -125,7 +125,14 @@ pkgs_core() {
       # curl, unzip and the TLS roots ship with macOS; the compilers come from
       # the Xcode command line tools, which is not a formula — see xcode_clt_*.
       # brotli is here because macOS ships the library but not the CLI.
-      echo gnupg git jq wget brotli btop htop tree ripgrep fd eza poppler radicale
+      #
+      # radicale has no Homebrew formula — confirmed live ("No available formula with the
+      # name radicale"), it is a pure-Python package normally installed via pip/pipx, not
+      # brew. Left out of a dev install rather than reached for pip here: officer-caldav
+      # (services.sh CORE_PROCESSES) is skipped to match on macOS, so nothing on this
+      # machine expects it to be present. The Linux lists above are untouched — a real
+      # package there, unaffected.
+      echo gnupg git jq wget brotli btop htop tree ripgrep fd eza poppler
       ;;
   esac
 }