Replace local network IPs (192.168.1.x) with Tailscale IPs for london-a and london-b in all scrape configs. This ensures consistent connectivity via Tailscale mesh regardless of network topology changes. Refs: PESO-80
- add missing --- to notification-policy.yml - prometheus.yml: replace commented-out template defaults with empty lists
- add missing --- to 13 more yml files - fix comment indentation in prometheus.yml