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>

next.config.mjs

@@ -9,6 +9,7 @@ const nextConfig = {
         // This is needed to copy the geoip-lite data files to the standalone build
         outputFileTracingIncludes: {
             '/api/track': ['./node_modules/geoip-lite/data/**/*'],
+            '/api/visitors': ['./node_modules/geoip-lite/data/**/*'],
         },
     },
     webpack: (config) => {