[Request] store historical transaction fiat value

[nahuhh]

Currently behavior:

• cake appears to recalculate the exchange rate of old transaction live.

(A 1xmr transaction from today (260usd) shows the same value as a 1xmr transaction a month ago ( shows 260usd)

Expected: 1 xmr transaction from a month ago shows 440$ (value at block time)

When receiving / sending a transaction, the transaction value should be stored locally (similar to the note) and should also be included in backups.

A picture is worth 1000 words.

This is what I'm looking for

[nahuhh]

Bump