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/jetbrains-toolbox/module.json

@@ -0,0 +1,27 @@
+{
+  "module": "jetbrains-toolbox",
+  "version": "1",
+  "requires": [
+    "x11-display"
+  ],
+  "tools": [
+    "toolbox_status",
+    "toolbox_restart",
+    "toolbox_check"
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/toolbox-tools",
+        "binary": "toolbox-tools",
+        "loads": [
+          "toolbox-tools"
+        ]
+      }
+    ]
+  }
+}