feat: add operational sync controls

app/web/templates/system.html

@@ -0,0 +1,33 @@
+{% extends "base.html" %}
+
+{% block title %}System - MyWhoosh Garmin Sync{% endblock %}
+
+{% block content %}
+<h1>System</h1>
+<p><a href="/">Back to dashboard</a></p>
+
+<dl>
+    <dt>Application version</dt>
+    <dd>{{ app_version }}</dd>
+
+    <dt>Sync interval (minutes)</dt>
+    <dd>{{ sync_interval_minutes }}</dd>
+
+    <dt>Last scheduler tick</dt>
+    <dd>{{ last_tick or "-" }}</dd>
+
+    <dt>Next scheduler tick</dt>
+    <dd>{{ next_tick or "-" }}</dd>
+
+    <dt>User count</dt>
+    <dd>{{ user_count }}</dd>
+
+    <dt>Activity count</dt>
+    <dd>{{ activity_count }}</dd>
+</dl>
+
+<form method="post" action="/sync-all">
+    <input type="hidden" name="csrf_token" value="{{ csrf_token }}">
+    <button type="submit">Sync all now</button>
+</form>
+{% endblock %}