feat(MemberOrder): add budget field to MemberOrder and MemberOrderHistory models

- Introduced a new budget field in both MemberOrder and MemberOrderHistory models to track budget amounts.
- Updated memberOrderService to handle budget in serialization and normalization processes.
- Enhanced OrdersPanel component to include budget input and display in the UI.
- Added German localization for the new budget term to ensure consistency across languages.

backend/models/MemberOrder.js

@@ -49,6 +49,11 @@ const MemberOrder = sequelize.define('MemberOrder', {
     allowNull: false,
     defaultValue: 0,
     field: 'paid_amount'
+  },
+  budget: {
+    type: DataTypes.DECIMAL(10, 2),
+    allowNull: false,
+    defaultValue: 0
   }
 }, {
   underscored: true,

backend/models/MemberOrderHistory.js

@@ -47,6 +47,11 @@ const MemberOrderHistory = sequelize.define('MemberOrderHistory', {
     allowNull: false,
     defaultValue: 0,
     field: 'paid_amount'
+  },
+  budget: {
+    type: DataTypes.DECIMAL(10, 2),
+    allowNull: false,
+    defaultValue: 0
   }
 }, {
   underscored: true,