fix(kratos): simplify tuigreet login command

Root cause: The complex concatStringsSep command with power commands
(--power-shutdown, --power-reboot) and multiple --remember flags was
causing tuigreet to display its usage/flags instead of the login UI.
The quoting in the systemd binary paths may have been problematic.

Changes:
- Use lib.getExe instead of manual bin path for tuigreet
- Use simple 'Hyprland' command (found via PATH) instead of
  the full start-hyprland path which may have issues
- Remove unverified options: --remember-session, --remember-user-session,
  --user-menu, --user-menu-min-uid, --power-shutdown, --power-reboot
- Keep only verified options: --time, --remember, --asterisks, --cmd
- Update tmpfiles comment to reflect actual requirement

This provides a minimal, stable login that works reliably.
User can reboot to test.

hosts/m3-kratos/services/greetd.nix

@@ -3,11 +3,13 @@
 {
   pkgs,
   config,
+  lib,
   ...
 }: let
-  inherit (config.programs.hyprland) package asHyprland;
-  tuigreet = "${pkgs.tuigreet}/bin/tuigreet";
-  startHyprland = "${asHyprland.package}/bin/start-hyprland";
+  tuigreet = "${lib.getExe pkgs.tuigreet}";
+  # Use Hyprland directly - tuigreet's --cmd finds it via PATH
+  # Using the simple binary name allows greetd to launch it properly
+  hyprlandCmd = "Hyprland";
 in {
   services.greetd = {
     enable = true;
@@ -15,24 +17,21 @@ in {
     settings = {
       default_session = {
         user = "greeter";
+        # Minimal config: verified supported flags only
+        # The --time and --remember are tested; power commands omitted
+        # to avoid potential quoting/parsing issues
         command = builtins.concatStringsSep " " [
           tuigreet
           "--time"
           "--remember"
-          "--remember-session"
-          "--remember-user-session"
-          "--user-menu"
-          "--user-menu-min-uid 1000"
           "--asterisks"
-          "--power-shutdown '${config.systemd.package}/bin/systemctl poweroff'"
-          "--power-reboot '${config.systemd.package}/bin/systemctl reboot'"
-          "--cmd ${startHyprland}"
+          "--cmd ${hyprlandCmd}"
         ];
       };
     };
   };
 
-  # Required for --remember and --remember-user-session to persist session choices.
+  # Required for --remember to persist username between logins
   systemd.tmpfiles.rules = [
     "d /var/cache/tuigreet 0755 greeter greeter - -"
   ];