feat: implement dropdowns for unit and location selection in inventory forms; add product sorting functionality

flutter/lib/core/forms/form_options.dart

@@ -0,0 +1,31 @@
+const inventoryLocationOptions = <String>[
+  'Kyl',
+  'Frys',
+  'Skafferi',
+];
+
+class UnitOption {
+  final String value;
+  final String label;
+
+  const UnitOption({required this.value, required this.label});
+}
+
+const unitOptions = <UnitOption>[
+  UnitOption(value: 'g', label: 'g (gram)'),
+  UnitOption(value: 'hg', label: 'hg (hektogram)'),
+  UnitOption(value: 'kg', label: 'kg (kilogram)'),
+  UnitOption(value: 'mg', label: 'mg (milligram)'),
+  UnitOption(value: 'ml', label: 'ml (milliliter)'),
+  UnitOption(value: 'cl', label: 'cl (centiliter)'),
+  UnitOption(value: 'dl', label: 'dl (deciliter)'),
+  UnitOption(value: 'l', label: 'l (liter)'),
+  UnitOption(value: 'krm', label: 'krm (kryddmatt)'),
+  UnitOption(value: 'tsk', label: 'tsk (tesked)'),
+  UnitOption(value: 'msk', label: 'msk (matsked)'),
+  UnitOption(value: 'st', label: 'st (styck)'),
+  UnitOption(value: 'port', label: 'port (portioner)'),
+  UnitOption(value: 'forp', label: 'forp (forpackning)'),
+  UnitOption(value: 'klyfta', label: 'klyfta'),
+  UnitOption(value: 'efter smak', label: 'efter smak'),
+];