feat(kmd): reduce KMD AUR from 5% to 0.01% starting at nS7HardforkHeight

[shamardy]

KMD interest calculation is adjusted to reduce AUR (Active User Rewards) from 5% to 0.01% starting from KMD block height 3484958 (Fri Jun 30 2023) according to KIP-0001

fixes #1840

[onur-ozkan]

LGTM. Do we need to ship this now or wait until the hardfork?

[shamardy]

Do we need to ship this now or wait until the hardfork?

This can be shipped now. The new AUR of 0,01% is applied to new utxos/transactions starting from nS7HardforkHeight and not old ones according to this comment GLEECBTC/komodo-daemon#584 (review)

Related code excerpt in mm2
https://github.com/KomodoPlatform/atomicDEX-API/blob/6a0820a425d64590ab2d49ee345628ae0272b37a/mm2src/coins/utxo.rs#L1635-L1637

[caglaryucekaya]

LGTM, I have just a minor comment

[DeckerSU]

Just curious to know, what's the purpose of introducing floating point arithmetic here, making a conversion from integer to float and vice versa, using drop_mutability! macros instead of simple:

    let accrued = if height >= N_S7_HARDFORK_HEIGHT {
        (value / 10_512_000) * minutes / 500
    } else {
        (value / 10_512_000) * minutes
    };