hub: shared host_detail_body sub-template + customer Host tab (v0.47.0 part 3)

- host_detail_body.html: {{define}}'d body sections extracted from
  host_detail.html; the standalone page is now chrome + the sub-template
- hosts.go: hostDetailData(host, r) view-model builder extracted from
  handleHostDetail (reused by both surfaces)
- store: ListHostsByCustomer (host_id order; the Host tab is a list by
  design - N hosts for a future HA cluster)
- customer Host tab renders one host_detail_body per host + cross-link;
  empty state when no host is enrolled
- tests: TestTemplates_CustomerHostTab(+_Empty), TestListHostsByCustomer

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Vvz1NCu22p8dGkRCpeX9re

hub/internal/store/store.go

@@ -1597,6 +1597,27 @@ func (s *Store) GetHostByCustomer(customerID string) (*Host, error) {
 	return h, err
 }
 
+// ListHostsByCustomer returns the customer's hosts ordered by host_id (v0.47.0 — the
+// customer page's Host tab is a LIST by design: 1 host today, N for a later HA cluster).
+// Uses the idx_hosts_customer index.
+func (s *Store) ListHostsByCustomer(customerID string) ([]Host, error) {
+	rows, err := s.db.Query(`SELECT `+hostSelectCols+
+		` FROM hosts WHERE customer_id = ? ORDER BY host_id`, customerID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var hosts []Host
+	for rows.Next() {
+		h, err := scanHost(rows.Scan)
+		if err != nil {
+			return nil, err
+		}
+		hosts = append(hosts, *h)
+	}
+	return hosts, rows.Err()
+}
+
 // ListHosts returns all hosts (debug / host-domain views).
 func (s *Store) ListHosts() ([]Host, error) {
 	rows, err := s.db.Query(`SELECT ` + hostSelectCols + ` FROM hosts ORDER BY host_id`)