Add slack and jetbrains-toolbox: one start each, the apps kept as found

Slack comes from the AUR and Toolbox from JetBrains' self-updating tarball,
so neither is declared: the host installs official packages only, and a
pinned archive would fight Toolbox's own updates. Slack's start and the
operator's i3 window rules become one node-display-session contribution,
because Slack's own launch-on-login is a symlink in ~/.config/autostart.
Toolbox keeps its own autostart entry as its one start. The shared
desktop.go header now names all four bundles.

modules/blueman/cmd/blueman-tools/desktop.go

@@ -1,7 +1,8 @@
 package main
 
-// desktop.go is the same file in the nextcloud-client and blueman bundles: a tray application of the
-// operator's graphical session, seen from the node's tool runtime (novox/hq ADR 0208).
+// desktop.go is the same file in the nextcloud-client, blueman, slack and jetbrains-toolbox bundles: a
+// tray application of the operator's graphical session, seen from the node's tool runtime (novox/hq
+// ADR 0208).
 //
 // The runtime is a system service running as the operator account (ADR 0175): it has the account's
 // uid and none of the session's environment. A tool that starts something on the desktop finds the

modules/blueman/cmd/blueman-tools/desktop_test.go

@@ -1,7 +1,7 @@
 package main
 
 // The fake machine the tests run against, and the tests of desktop.go. The same in the
-// nextcloud-client and blueman bundles.
+// nextcloud-client, blueman, slack and jetbrains-toolbox bundles.
 
 import (
 	"context"