Split /api/v1/state into dedicated resource endpoints: - /api/v1/operator, /api/v1/central-domain - /api/v1/ddns/config, /api/v1/dns/settings - /api/v1/dhcp/config (moved from /dnsmasq/dhcp/) - /api/v1/nftables/config, /api/v1/haproxy/routes Each page now talks to its own resource instead of deep-merging a blob. Removes useConfig hook, CentralState type, and legacy config methods.