update: system update & refactor

# Breaking Changes
- sops location movod to "system/dev/<dev-name>/sops/sops-conf.nix"
- flake devices declaration changes
- whole flake update

system/dev/dn-server/services/mail-server.nix

@@ -0,0 +1,58 @@
+{ config, ... }:
+let
+  inherit (config.systemConf) username;
+in
+{
+  mail-server =
+    let
+      domain = "net.dn";
+    in
+    {
+      inherit domain;
+
+      enable = true;
+      openFirewall = true;
+      configureNginx = true;
+      hostname = "mx1";
+      extraDomains = [
+        "mail.${domain}"
+      ];
+      caFile = "" + ../../../extra/ca.crt;
+      rootAlias = "${username}";
+      networks = [
+        "127.0.0.0/8"
+        "10.0.0.0/24"
+      ];
+      virtual = ''
+        admin@${domain} ${username}@${domain}
+        postmaster@${domain} ${username}@${domain}
+      '';
+      webmail = {
+        enable = true;
+        hostname = "mail.${domain}";
+      };
+      keycloak = {
+        dbSecretFile = config.sops.secrets."oauth/password".path;
+        adminAccountFile = config.sops.secrets."oauth/adminEnv".path;
+      };
+      ldap = {
+        filter = "(&(objectClass=inetOrgPerson)(objectClass=mailRoutingObject)(uid=%{user | username}))";
+        extraAuthConf = ''
+          auth_username_format = %{user | lower}
+          fields {
+            user = %{ldap:mail}
+            password = %{ldap:userPassword}
+          }
+        '';
+        secretFile = config.sops.secrets."ldap/password".path;
+        webSecretFile = config.sops.secrets."ldap/env".path;
+      };
+      rspamd = {
+        secretFile = config.sops.secrets."rspamd".path;
+        trainerSecretFile = config.sops.secrets."rspamd-trainer".path;
+      };
+      dovecot.oauth = {
+        enable = true;
+      };
+    };
+}