Remilia: add SNM and vault-agent

hosts/servers/remilia/mailserver.nix

@@ -0,0 +1,16 @@
+{ config, pkgs, ... }:
+{
+  mailserver = {
+    enable = true;
+    fqdn = "mail.weirdnatto.in";
+    domains = [ "weirdnatto.in" ];
+    loginAccounts = {
+      "natto@weirdnatto.in" = {
+        hashedPasswordFile = "/var/secrets/natto@weirdnatto.in.key";
+        aliases = ["@weirdnatto.in"];
+      };
+    };
+    enablePop3 = false;
+    enablePop3Ssl = false;
+  };
+}