feat: Flake | revamp entire flake (#1)

Reviewed-on: #1

hosts/common/optional/services/greetd.nix

@@ -0,0 +1,16 @@
+{
+  pkgs,
+  ...
+}:
+
+{
+  services.greetd = {
+    enable = true;
+    settings = {
+      default_session = {
+        command = "${pkgs.greetd.tuigreet}/bin/tuigreet --greeting 'Welcome to NixOS!' --asterisks --remember --remember-user-session --time --cmd ${pkgs.hyprland}/bin/Hyprland";
+        user = "greeter";
+      };
+    };
+  };
+}