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

default/hypr/apps/hermes.lua

@@ -1,7 +1,5 @@
 -- Hermes Desktop's frameless HUD manages its own geometry.
 o.window({ class = "^Hermes$", title = "^Hermes HUD$" }, {
-  tag = "-default-opacity",
   float = true,
   border_size = 0,
-  opacity = "1 1",
 })