feat: 添加预算管理功能，包括其handler、service和repository层。

internal/handler/budget_handler.go

@@ -98,6 +98,7 @@ func (h *BudgetHandler) GetBudget(c *gin.Context) {
 }
 
 // GetAllBudgets handles GET /api/v1/budgets
+// Returns budgets with calculated spent and progress fields
 func (h *BudgetHandler) GetAllBudgets(c *gin.Context) {
 	// Get user ID from context
 	userID, exists := c.Get("user_id")
@@ -106,7 +107,8 @@ func (h *BudgetHandler) GetAllBudgets(c *gin.Context) {
 		return
 	}
 
-	budgets, err := h.service.GetAllBudgets(userID.(uint))
+	// Use GetAllBudgetsWithProgress to return budgets with spent and progress calculated
+	budgets, err := h.service.GetAllBudgetsWithProgress(userID.(uint))
 	if err != nil {
 		api.InternalError(c, "Failed to get budgets")
 		return