tracing issue of transaction price and precision of currency

[Kilerd]

currently while parsing the beancount example file into zhang, there are lots of error thrown by balance check system, there are two main cause of it:

one is precision issue

2015-04-13 * "Investing 60% of cash in RGAGX"
  Assets:US:Vanguard:RGAGX                          8.605 RGAGX {83.67 USD, 2015-04-13}
  Assets:US:Vanguard:Cash                         -719.98 USD

8.605 * 83.67 = 719.98035, which is not equals to 719.98. if we have the default 2 decimal place precision for this commodity, then it will round down as 719.98, then the transaction is balanced

the second one is the price calculator, for now though zhang parser can accept the syntax Assets:US:ETrade:VEA -4 VEA {148.59 USD, 2017-03-19} @ 145.72 USD, but the calculator did not use the cost and single price info to calculate the final cost.

we should allow use to modify currency/commodity's precision and round direction via commodity directive's meta

and should calculate the transaction postings' price presentation, there are some scenario of posting's price

NO	Posting directive	unit	cost	single price	total price
1	Account
2	Account 10 USD	10 USD
3	Account 10 USD { 7 CNY }	10 USD	7 CNY
4	Account 10 USD { 7 CNY, 2022-06-02 }	10 USD	7 CNY, 2022-06-02
5	Account 10 USD @ 7 CNY	10 USD		7 CNY
6	Account 10 USD @@ 70 CNY	10 USD			70 CNY
7	Account 10 USD { 7 CNY } @ 6.9 CNY	10 USD	7 CNY	6.9 CNY
8	Account 10 USD { 7 CNY, 2022-06-02 } @ 6.9 CNY	10 USD	7 CNY, 2022-06-02	6.9 CNY

so the issue need to handle

• commodity list
• comodity's precision and round way
• parsing posting into structural posting object and return them via GraphQL
• transaction balance logic based on round way and precision
• frontend UI change

[Kilerd]

need to include the issue #65