feat(pi): add Android app download link to the settings page

templates/settings.html

@@ -46,6 +46,25 @@
 
 <form id="settings-form">
 
+    {# ═══ Android app ═══════════════════════════════════════════════════ #}
+    <div class="settings-section">Android app</div>
+    <div class="card shadow-sm mb-3 settings-card">
+        <div class="card-header py-2">
+            <i class="fab fa-android"></i>
+            <p class="text-dark m-0 fw-bold small">Companion app</p>
+        </div>
+        <div class="card-body py-3">
+            <p class="small text-muted mb-2">
+                Download the yaris-obd Android companion app from the car hotspot.
+                The Pi mirrors the latest build from the server automatically
+                when internet is available.
+            </p>
+            <a class="btn btn-primary btn-sm" href="/app" target="_blank" rel="noopener">
+                <i class="fas fa-download me-1"></i>Open app download page
+            </a>
+        </div>
+    </div>
+
     {# ═══ Car & identity ═══════════════════════════════════════════════ #}
     <div class="settings-section">Car &amp; identity</div>
     <div class="card shadow-sm mb-3 settings-card">