Make application transparency opt-in (#14253)

* Make application transparency opt-in

* Use the transparency helper for Kanagawa

* Address transparency review findings

* Toggle transparency for opaque windows too

config/hypr/looknfeel.lua

@@ -1,5 +1,10 @@
 -- Change the default Omarchy look'n'feel.
 
+-- Opt another application in to Omarchy's standard transparency.
+-- Find its class with: hyprctl clients
+-- o.transparent_window("my-app")
+-- o.transparent_window("my-app", "0.9 0.85") -- Custom active/inactive opacity.
+
 -- https://wiki.hypr.land/Configuring/Basics/Variables/#general
 -- hl.config({
 --   general = {