Allow customizing the screensaver logo (#863)

* check for custom screensaver logo or fall back to default

* move logo location to omarchy config folder

* fix missed location check

* add menu item to copy logo.txt and open in editor

* move to setup menu

* Just always use a user-editable screensaver.txt file

* No longer needed

* Be clearer

---------

Co-authored-by: Christopher Moore <cmoore@yozu.co.uk>
Co-authored-by: David Heinemeier Hansson <david@hey.com>

migrations/1755867743.sh

@@ -0,0 +1,3 @@
+echo "Copy Omarchy logo to ~/.config/omarchy/screensaver.txt so screensaver can be personalized"
+
+cp $OMARCHY_PATH/logo.txt ~/.config/omarchy/screensaver.txt