Members page: show a live total member count

Count every membership account (free and paid together) on each page
load and show it under the headline; no per-tier numbers. Hidden when
there are no members.

Also correct the reference tiers.eom.json and service-groups.eom.json
to the real LDAP DNs (ou=Memberships; ou=<Service>,ou=Services), which
now match the ansible-role-www defaults.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

htdocs/static/membership.css

@@ -5,6 +5,8 @@
 .member-main { padding-bottom: 4rem; }
 .member-hero { padding-block: clamp(3rem, 8vw, 6rem); }
 .member-hero h1 { font-size: clamp(2.8rem, 6vw, 5rem); max-width: 900px; }
+.member-count { color: var(--muted); font-size: 1.1rem; }
+.member-count strong { color: var(--accent-strong); font-size: 1.6rem; font-variant-numeric: tabular-nums; }
 .member-intro { max-width: 700px; color: var(--muted); font-size: 1.2rem; }
 .member-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 1rem; }
 .member-actions form { margin: 0; }