feat(status-page): add public status page at status.mana.how

- scripts/generate-status-page.sh: Shell-Script das VictoriaMetrics abfragt
  und eine statische HTML-Statusseite generiert (probe_success + response times)
- docker-compose.macmini.yml: mana-status-gen Container (Alpine, jq, curl)
  schreibt alle 60s nach /Volumes/ManaData/landings/status/
- docker/nginx/landings.conf: status.mana.how vHost mit Cache-Control: no-store
- cloudflared-config.yml: status.mana.how → localhost:4400

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

docker/nginx/landings.conf

@@ -106,3 +106,25 @@ server {
     index index.html;
     include /etc/nginx/snippets/landing-common.conf;
 }
+
+# status.mana.how — Public Status Page (generated by mana-status-gen every 60s)
+server {
+    listen 80;
+    server_name status.mana.how;
+    root /srv/landings/status;
+    index index.html;
+
+    add_header X-Frame-Options "SAMEORIGIN" always;
+    add_header X-Content-Type-Options "nosniff" always;
+    add_header Cache-Control "no-store" always;
+
+    location / {
+        try_files $uri /index.html;
+    }
+
+    location /health {
+        access_log off;
+        return 200 "healthy\n";
+        add_header Content-Type text/plain;
+    }
+}