feat: declare user quadlet files via NixOS tmpfiles

modules/common/podman.nix

@@ -1,8 +1,29 @@
 { config, lib, pkgs, ... }:
+
+let
+  nginxQuadlet = pkgs.writeText "nginx-example.container" ''
+    [Container]
+    Image=nginx:latest
+    PublishPort=9999:80
+
+    [Service]
+    Restart=always
+
+    [Install]
+    WantedBy=default.target
+  '';
+in
 {
   virtualisation.podman = {
     enable = true;
-    # Rootless containers by default
+    # Rootless containers via user quadlets
-    # Quadlet files in ~/.config/containers/systemd/ are auto-detected
   };
+
+  # Write quadlet files into the containers user's config directory
+  systemd.tmpfiles.rules = [
+    "d /var/lib/containers/.config 0755 containers containers -"
+    "d /var/lib/containers/.config/containers 0755 containers containers -"
+    "d /var/lib/containers/.config/containers/systemd 0755 containers containers -"
+    "L+ /var/lib/containers/.config/containers/systemd/nginx-example.container - - - - ${nginxQuadlet}"
+  ];
 }