hotfix(calamares): make COSMIC greeter actually work on online installs

Chain COSMIC as the first branch in DMgreetd.set_autologin so
cosmic-greeter-start is picked before gtkgreet/tuigreet/ddlm fallbacks.
Also set the cosmic-greeter user and general.service so the generated
config.toml matches upstream cosmic-greeter.toml. Gate on the selected
desktop being COSMIC. pkgrel 11 -> 12.

PS: as the maintainer, a hotfix release will drop shortly after I finish
suffering through a Gentoo install.

packages/calamares/PKGBUILD

@@ -5,7 +5,7 @@
 _pkgname="calamares"
 pkgname="$_pkgname"
 pkgver=3.4.2
-pkgrel=11
+pkgrel=12
 pkgdesc="Distribution-independent installer framework"
 url="https://codeberg.org/Calamares/calamares"
 license=("GPL-3.0-or-later")
@@ -56,9 +56,7 @@ build() {
   sed -i "/DesktopEnvironment('\/usr\/bin\/Hyprland', 'hyprland'),/a\    DesktopEnvironment('/usr/bin/start-cosmic', 'cosmic')," \
     "$_pkgsrc_dir/src/modules/displaymanager/main.py"
 
-  sed -i '/"ddlm --target " + de_command/a\
-        elif os.path.exists(self.os_path("usr/bin/cosmic-greeter-start")):\
-            self.config_data["default_session"]["command"] = "cosmic-greeter-start"' \
+  sed -i 's|        if os.path.exists(self.os_path("usr/bin/gtkgreet")) and os.path.exists(self.os_path("usr/bin/cage")):|        if os.path.exists(self.os_path("usr/bin/cosmic-greeter-start")) and de_command == "/usr/bin/start-cosmic":\n            self.config_data["default_session"]["command"] = "cosmic-greeter-start"\n            self.config_data["default_session"]["user"] = "cosmic-greeter"\n            self.config_data["general"] = dict(service = "cosmic-greeter")\n        elif os.path.exists(self.os_path("usr/bin/gtkgreet")) and os.path.exists(self.os_path("usr/bin/cage")):|' \
     "$_pkgsrc_dir/src/modules/displaymanager/main.py"
 
   local _cmake_options=(