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>

niri/config.kdl

@@ -130,10 +130,16 @@ window-rule {
     default-floating-position x=-9999 y=-9999
 }
 
-// RuneLite (Java app-id pattern - verify with: niri msg pick-window)
+// Bolt Launcher
+window-rule {
+    match app-id="^bolt-launcher$"
+    open-floating true
+}
+
+// RuneLite
 window-rule {
     match app-id="^(net-runelite-client-RuneLite|runelite|RuneLite)$"
-    open-maximized true
+    open-floating true
     border {
         off
     }