Add optional Home Assistant integration for battery percentage tracking

templates/device_detail.html

@@ -28,6 +28,12 @@
       <td style="border:none;">{{ device.notes }}</td>
     </tr>
     {% endif %}
+    {% if ha_enabled and device.ha_entity_id %}
+    <tr>
+      <td style="padding:0.3rem 1rem 0.3rem 0;font-weight:600;color:#64748b;border:none;">HA Entity</td>
+      <td style="border:none;"><code>{{ device.ha_entity_id }}</code></td>
+    </tr>
+    {% endif %}
   </table>
 </div>
 
@@ -99,13 +105,22 @@ function addInstallRow() {
     <div class="table-wrap">
       <table class="responsive-table">
         <thead>
-          <tr><th>Label</th><th>Brand</th><th>Notes</th><th>Actions</th></tr>
+          <tr><th>Label</th><th>Brand</th>{% if ha_enabled %}<th>Bat %</th>{% endif %}<th>Notes</th><th>Actions</th></tr>
         </thead>
         <tbody>
           {% for b in installed %}
           <tr>
             <td data-label="Label"><a href="{{ url_for('battery_detail', battery_id=b.id) }}">{{ b.label }}</a></td>
             <td data-label="Brand">{{ b.brand }}</td>
+            {% if ha_enabled %}
+            <td data-label="Bat %">
+              {% if b.battery_percentage is not none %}
+                {% if b.battery_percentage < 20 %}
+                  <span class="badge badge-warning" title="Low — consider replacing">⚠ {{ b.battery_percentage }}%</span>
+                {% else %}{{ b.battery_percentage }}%{% endif %}
+              {% else %}—{% endif %}
+            </td>
+            {% endif %}
             <td data-label="Notes" class="text-muted">{{ b.notes or '—' }}</td>
             <td data-label="Actions">
               <form class="inline" method="post" action="{{ url_for('battery_unassign', battery_id=b.id) }}">
@@ -180,6 +195,14 @@ function addInstallRow() {
       <label for="edit-notes">Notes</label>
       <textarea id="edit-notes" name="notes">{{ device.notes or '' }}</textarea>
     </div>
+    {% if ha_enabled %}
+    <div class="form-group">
+      <label for="edit-ha-entity">Home Assistant Entity ID</label>
+      <input type="text" id="edit-ha-entity" name="ha_entity_id"
+             value="{{ device.ha_entity_id or '' }}"
+             placeholder="e.g. sensor.tv_remote_battery">
+    </div>
+    {% endif %}
     <button class="btn btn-primary" type="submit">Save Changes</button>
   </form>
 </div>