Add mouse battery widget, Bolt Launcher rule, cursor size; fix theme symlink

- waybar: add custom/mouse-battery module and mouse-battery.sh script
- niri: add Bolt Launcher floating rule; switch RuneLite to floating
- environment.d: set XCURSOR_SIZE=36
- install.sh: add symlinks for theme/colors.css and mouse-battery.sh (fixes @import path)
- .gitignore: exclude nohup.out

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

waybar/config.jsonc

@@ -5,7 +5,13 @@
 
   "modules-left": ["niri/workspaces"],
   "modules-center": ["clock"],
-  "modules-right": ["cpu", "temperature", "custom/power-profile", "custom/fan-profile", "pulseaudio", "network", "battery", "tray"],
+  "modules-right": ["cpu", "temperature", "custom/power-profile", "custom/fan-profile", "pulseaudio", "network", "battery", "custom/mouse-battery", "tray"],
+  "custom/mouse-battery": {
+    "exec": "~/.config/waybar/mouse-battery.sh",
+    "interval": 60,
+    "format": " {output}",
+    "tooltip": false
+  },
 
   "cpu": {
     "format": "  {usage}%",