Wire up visitor metrics from webserver DB and fix uptime monitoring

- Read visitors from /server_storage/visitors.db (webserver's DB) instead of
  admin dash's own table; geoip lookups at query time for globe markers
- Globe card now shows 24h, 7d, and all-time unique visitor counts
- Uptime monitor: Nextcloud via host.docker.internal for Docker networking,
  Website and Gitea monitored on public domains
- UptimeCard uses real hourly history bars instead of Math.random() mock
- docker-compose: mount /server_storage:ro, add extra_hosts for Linux compat

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

monitor.js

@@ -6,7 +6,7 @@ const fetch = require('node-fetch'); // Native fetch in Node 18, but let's be sa
 const SERVICES = [
     { name: 'Website', url: 'https://www.akkolli.net' },
     { name: 'Gitea', url: 'https://code.akkolli.net' },
-    { name: 'Nextcloud', url: 'http://localhost:6060' },
+    { name: 'Nextcloud', url: 'http://host.docker.internal:6060' },
 ];
 
 async function monitor() {