Add cross-app super admin group; rename Executive page to Overview

- app_super_admin is a new cross-app LDAP group (also recognized by proxy
  and jump-host) that grants full admin here regardless of app_sso_admin
  membership: bypassed centrally in utils/permission.js's byGroup, folded
  into GET /api/user/me's isAdmin flag, and added to nav/forceLogin gates
  alongside app_sso_admin.
- Renamed the Executive page to Overview (route, view, API path
  /api/metrics/overview, nav label, docs), keeping /executive as a 301
  redirect alongside the existing /admin, /notifications, /dashboard
  legacy redirects.

nodejs/routes/api_metrics.js

@@ -3,8 +3,8 @@ const router = require('express').Router();
 const permission = require('../utils/permission');
 const metrics = require('../utils/metrics');
 
-// /api/metrics/executive
-router.get('/executive', async (req, res, next) => {
+// /api/metrics/overview
+router.get('/overview', async (req, res, next) => {
     try {
         await permission.byGroup(req.user, ['app_sso_admin']);