feat(ui): simplify to 3-button manage layout and remove drawer grouping

server.js

@@ -188,6 +188,30 @@ app.patch('/api/items/:id/quantity', (req, res) => {
   }
 });
 
+// Add whole packet (+1 full pack size)
+app.post('/api/items/:id/add-packet', (req, res) => {
+  try {
+    const count = parseInt(req.body.count, 10) || 1;
+    const item = db.addPacket(req.params.id, count);
+    if (!item) return res.status(404).json({ error: 'Item not found' });
+    res.json(item);
+  } catch (err) {
+    res.status(500).json({ error: err.message });
+  }
+});
+
+// Remove whole packet (-1 full pack size)
+app.post('/api/items/:id/remove-packet', (req, res) => {
+  try {
+    const count = parseInt(req.body.count, 10) || 1;
+    const item = db.removePacket(req.params.id, count);
+    if (!item) return res.status(404).json({ error: 'Item not found' });
+    res.json(item);
+  } catch (err) {
+    res.status(500).json({ error: err.message });
+  }
+});
+
 // Delete item
 app.delete('/api/items/:id', (req, res) => {
   try {