quickshell: drop support for 0.2, require 0.3+

- Remove all compat code
- Rewire LegacyNetworkService to use Quickshell.Networking
- Add parentWindow to settings child windows

core/internal/config/embedded/niri.kdl

@@ -250,12 +250,6 @@ window-rule {
     match app-id="zoom"
     open-floating true
 }
-// Open dms windows as floating by default
-window-rule {
-    match app-id=r#"org.quickshell$"#
-    match app-id=r#"com.danklinux.dms$"#
-    open-floating true
-}
 debug {
     honor-xdg-activation-with-invalid-serial
 }