Add size-in-label checkbox to battery add form

tests/test_acceptance.py

@@ -48,7 +48,7 @@ def test_dashboard_loads(seeded_client):
 def test_battery_add_get_renders(client):
     resp = client.get("/battery/add")
     assert resp.status_code == 200
-    assert b"brandCounts" in resp.data
+    assert b"prefixMaxNums" in resp.data
 
 
 def test_battery_add_brand_counts_reflects_existing(seeded_client):