Add oauth2-proxy cookie secret to configuration and update secrets.yaml for enhanced security management

modules/servers/oauth2-proxy.nix

@@ -14,6 +14,10 @@ in
       sopsFile = ../../secrets/env.yaml;
       restartUnits = [ "oauth2-proxy.service" ];
     };
+    sops.secrets.oauth2-proxy-cookie = {
+      sopsFile = ../../secrets/secrets.yaml;
+      restartUnits = [ "oauth2-proxy.service" ];
+    };
     services.oauth2-proxy = {
       inherit (cfg) enable;
       provider = "keycloak-oidc";
@@ -29,6 +33,7 @@ in
         expire = "168h";
         refresh = "1h";
         domain = ".lebubu.org";
+        secret = config.sops.secrets.oauth2-proxy-cookie.path;
       };
       extraConfig = {
         skip-auth-route = [ "^/ping$" ];