patiodeck: add steam deck LCD host

hosts/patiodeck/impermanence.nix

@@ -0,0 +1,48 @@
+{
+  username,
+  ...
+}:
+{
+  environment.persistence."/persistent" = {
+    hideMounts = true;
+    directories = [
+      "/var/log"
+      "/var/lib/systemd/coredump"
+      "/var/lib/nixos"
+      "/var/lib/systemd/timers"
+      # agenix identity sealed by the TPM
+      {
+        directory = "/var/lib/agenix";
+        mode = "0700";
+        user = "root";
+        group = "root";
+      }
+    ];
+
+    files = [
+      "/etc/ssh/ssh_host_ed25519_key"
+      "/etc/ssh/ssh_host_ed25519_key.pub"
+      "/etc/ssh/ssh_host_rsa_key"
+      "/etc/ssh/ssh_host_rsa_key.pub"
+      "/etc/machine-id"
+    ];
+
+    users.root = {
+      files = [
+        ".local/share/fish/fish_history"
+      ];
+    };
+  };
+
+  # bind mount home directory from persistent storage
+  fileSystems."/home/${username}" = {
+    device = "/persistent/home/${username}";
+    fsType = "none";
+    options = [ "bind" ];
+    neededForBoot = true;
+  };
+
+  systemd.tmpfiles.rules = [
+    "d /etc 755 root"
+  ];
+}