First commit of claude's rework in django + vanillajs fronted

apps/common/serializer_helpers.py

@@ -0,0 +1,22 @@
+"""Shared serializer helper functions used across multiple apps."""
+
+
+def ammo_detail(ammo):
+    if ammo is None:
+        return None
+    cal = ammo.caliber
+    return {
+        'id': ammo.id, 'brand': ammo.brand, 'name': ammo.name,
+        'caliber_detail': {'id': cal.id, 'name': cal.name} if cal else None,
+    }
+
+
+def batch_detail(batch):
+    if batch is None:
+        return None
+    return {
+        'id': batch.id,
+        'recipe_name': batch.recipe.name,
+        'powder': str(batch.powder),
+        'powder_charge_gr': str(batch.powder_charge_gr),
+    }