Paginate activity history and aggregate dashboard totals in SQL

app/templates/dashboard.html

@@ -25,6 +25,6 @@
 <p class="section-description">Fastest stretches within your runs, including stops. PR badges mark records set at the time of the run; your first effort establishes a record.</p>
 <div class="records-grid">{% for record in record_book.records %}<a class="record-card" href="{{ url_for('web.activity', activity_id=record.activity.id) }}"><span>{{ record.label }}</span><strong>{{ record.seconds|duration }}</strong><small>{{ record.activity.started_at|localdate(profile.timezone) }} · {{ record.activity.title }}</small></a>{% else %}<p class="field-help">Import a run with recorded distance and timestamps to establish your first record.</p>{% endfor %}</div></section>
 {% endif %}
-<section class="panel activities-panel"><div class="section-head"><div><span class="eyebrow">SESSION HISTORY</span><h2>{{ 'Your activities' if personal else 'Shared activities' }}</h2></div><span class="subtle-label">{{ rows|length }} activities</span></div>{% include '_activities.html' %}</section>
+<section class="panel activities-panel" id="history"><div class="section-head"><div><span class="eyebrow">SESSION HISTORY</span><h2>{{ 'Your activities' if personal else 'Shared activities' }}</h2></div><span class="subtle-label">{{ stats.count }} activities</span></div>{% include '_activities.html' %}</section>
 {% endblock %}
 {% block scripts %}<script src="{{ url_for('static',filename='vendor/leaflet.js') }}"></script><script src="{{ url_for('static',filename='vendor/chart.umd.js') }}"></script><script src="{{ url_for('static',filename='dashboard.js') }}"></script>{% endblock %}