重构预算管理模块，添加预算记录和服务，更新相关API，优化预算统计逻辑

Web/src/constants/enums.js

@@ -0,0 +1,27 @@
+/**
+ * 预算周期类型
+ */
+export const BudgetPeriodType = {
+  Week: 0,
+  Month: 1,
+  Year: 2,
+  Longterm: 3
+}
+
+/**
+ * 预算类别
+ */
+export const BudgetCategory = {
+  Expense: 0,
+  Income: 1,
+  Savings: 2
+}
+
+/**
+ * 交易类型 (与后端 TransactionType 对应)
+ */
+export const TransactionType = {
+  Expense: 0,
+  Income: 1,
+  None: 2
+}