refactor: moved nixos modules to dendrite pattern

modules/nixos/ssh.nix

@@ -0,0 +1,46 @@
+{...}: {
+  flake.nixosModules.nixos-ssh = {
+    lib,
+    config,
+    ...
+  }: {
+    options = {
+      services.openssh.impermanence.enable = lib.mkOption {
+        type = lib.types.bool;
+        default = config.services.openssh.enable && config.storage.impermanence.enable;
+      };
+    };
+
+    config = {
+      services = {
+        openssh = {
+          enable = true;
+          ports = [22];
+          settings = {
+            PasswordAuthentication = false;
+            UseDns = true;
+            X11Forwarding = false;
+          };
+        };
+      };
+
+      storage.datasets.replicate."system/root" = {
+        files = lib.mkIf config.services.openssh.impermanence.enable (builtins.listToAttrs (
+          lib.lists.flatten (
+            builtins.map (hostKey: [
+              {
+                name = hostKey.path;
+                value = {enable = true;};
+              }
+              {
+                name = "${hostKey.path}.pub";
+                value = {enable = true;};
+              }
+            ])
+            config.services.openssh.hostKeys
+          )
+        ));
+      };
+    };
+  };
+}