Remove unused invite and SSH-key user features

Both were dead/incomplete: POST /api/user/key called a nonexistent
User.addSSHkey, and the invite flow (POST /api/user/invite, User.invite,
User.addByInvite, InviteToken) had no consumer or UI. Drop the routes, the
InviteToken model, and the per-backing invite methods.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

nodejs/models/user_ldap.js

@@ -1,7 +1,7 @@
 'use strict';
 
 const { Client, Attribute, Change } = require('ldapts');
-const {Token, InviteToken} = require('./token');
+const {Token} = require('./token');
 const conf = require('@simpleworkjs/conf').ldap;
 
 const client = new Client({
@@ -141,17 +141,6 @@ User.exists = async function(data){
 	}
 };
 
-User.invite = async function(){
-	try{
-		let token = await InviteToken.add({created_by: this.username});
-		
-		return token;
-
-	}catch(error){
-		throw error;
-	}
-};
-
 User.login = async function(data){
 	try{
 		let user = await this.get(data.username);