Make DNS servers fully dynamic from config.json

DNS server IDs (dns1, dns2, dns3) were hardcoded throughout the frontend
and backend. Now config.json's dnsServers object is the single source of
truth — adding or removing a DNS server in config automatically updates
the dashboard cards, credential modal, health checks, and probes.

- credentials.js: rebuild modal sections dynamically from SITE.dnsServers
- globals.js: add getPrimaryDnsId() helper for primary DNS lookups
- service-create.js, service-infrastructure.js: use dynamic DNS ID
- startup-validator.js: dynamic topCardServices from config
- middleware.js: add license endpoints to public routes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

status/js/core/service-create.js

@@ -284,7 +284,7 @@
       const results = { dns: null, caddy: null, dashboard: false };
 
       if (createDns) {
-        const adminToken = window.getToken('dns2', 'admin');
+        const adminToken = window.getToken(getPrimaryDnsId(), 'admin');
         if (adminToken) {
           try {
             const dnsResponse = await secureFetch('/api/v1/dns/record', {
@@ -457,7 +457,7 @@
     const healthCheck = document.getElementById('health-check-input')?.value || '';
     const timeout = document.getElementById('timeout-input')?.value || 30;
 
-    const dnsToken = window.getToken('dns2', 'admin');
+    const dnsToken = window.getToken(getPrimaryDnsId(), 'admin');
 
     if (!name || !port || !ip) {
       showNotification('Please fill in Name, Port, and IP Address', 'warning');