Add Slack to Install > Service (#14434)

Slack is one of the most popular apps people install from the AUR. It now
ships from the Omarchy package repository as slack-desktop, with native
x86_64 and aarch64 builds. Install it the same way as Bitwarden: one menu
entry that installs the package and then launches Slack. The commercial
apps page of the manual gets a matching section.

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

default/omarchy/omarchy-menu.jsonc

@@ -227,6 +227,7 @@
   "install.service.dropbox": {"icon":"","label":"Dropbox","disabled":"omarchy-pkg-present dropbox","action":"omarchy-launch-floating-terminal-with-presentation omarchy-install-service-dropbox"},
   "install.service.spotify": {"icon":"󰓇","label":"Spotify","disabled":"omarchy-pkg-present spotify","action":"omarchy-launch-floating-terminal-with-presentation omarchy-install-service-spotify"},
   "install.service.signal": {"icon":"󰭹","label":"Signal","disabled":"omarchy-pkg-present signal-desktop","action":"omarchy-launch-floating-terminal-with-presentation omarchy-install-service-signal"},
+  "install.service.slack": {"icon":"󰒱","label":"Slack","disabled":"omarchy-pkg-present slack-desktop","action":"omarchy-install-and-launch Slack slack-desktop slack"},
   "install.service.tailscale": {"icon":"","label":"Tailscale","disabled":"omarchy-pkg-present tailscale","action":"omarchy-launch-floating-terminal-with-presentation omarchy-install-service-tailscale"},
   "install.service.nordvpn": {"icon":"󱇱","label":"NordVPN","disabled":"omarchy-pkg-present nordvpn-bin","action":"omarchy-launch-floating-terminal-with-presentation omarchy-install-service-nordvpn"},
   "install.service.once": {"icon":"󰏖","label":"ONCE","disabled":"omarchy-pkg-present once-bin","action":"omarchy-launch-floating-terminal-with-presentation omarchy-install-service-once"},