waybar: collapse tray icons behind a click-to-reveal drawer

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

waybar/config.jsonc

@@ -5,7 +5,7 @@
 
   "modules-left": ["niri/workspaces"],
   "modules-center": ["custom/clock"],
-  "modules-right": ["cpu", "temperature", "custom/power-profile", "custom/fan-profile", "pulseaudio", "network", "battery", "custom/mouse-battery", "tray"],
+  "modules-right": ["cpu", "temperature", "custom/power-profile", "custom/fan-profile", "pulseaudio", "network", "battery", "custom/mouse-battery", "group/tray-drawer"],
   "custom/mouse-battery": {
     "exec": "~/.config/waybar/mouse-battery.sh",
     "interval": 60,
@@ -73,6 +73,22 @@
     "spacing": 8
   },
 
+  "group/tray-drawer": {
+    "orientation": "horizontal",
+    "drawer": {
+      "transition-duration": 200,
+      "children-class": "tray-drawer-child",
+      "transition-left-to-right": true,
+      "click-to-reveal": true
+    },
+    "modules": ["custom/tray-arrow", "tray"]
+  },
+
+  "custom/tray-arrow": {
+    "format": "",
+    "tooltip": false
+  },
+
   "network": {
     "format-wifi": "  {essid}",
     "format-ethernet": "󰈀",