Add MOT/insurance renewal hints, table service card, and favicon

- Renewal tracking: compute due/overdue status from the most recent
  mot/insurance event (renewal_months, renewal_due_soon_days settings),
  surfaced on the service card and dashboard.
- Service-status card metrics now render as a two-column label/value
  table with row separators instead of wrapping auto-fill grid cells.
- Add a bicycle favicon (favicon.svg) to base + login templates.

Co-Authored-By: opencode <opencode@users.noreply.github.com>

app/templates/base.html

@@ -4,6 +4,7 @@
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>{% block title %}bike-admin{% endblock %}</title>
+<link rel="icon" href="/static/favicon.svg" type="image/svg+xml">
 <link rel="stylesheet" href="/static/main.css">
 <script src="/static/htmx.min.js" defer></script>
 </head>