Bug: Max amount button rounds up

[plor]

Describe the bug

On the Minion transfer, if you click the max button it reduces some precision for the ERC-20 and rounds up, sometimes resulting in failed transactions.

I've loaded a test DAO with 0.00555555555555 WETH on rinkeby. If you need membership let me know and I'll vote you in (or reproduce yourself).

To Reproduce
Steps to reproduce the behavior:

1. Go to https://app.daohaus.club/dao/0x4/0x3259342eed7cfa03fab8b0854fe6836a40bd1e93/vaults/minion/0x7605789454f0845b55a5fe0284d3a675aef7fb26
2. Click on Transfer > Max > Submit
3. See payment rounded up
4. If you try to execute, see it fail

Expected behavior

Max should transfer exactly what is available in the vault (at correct precision).

Actual behavior

Max button rounds up and exceeds actual max if number after precision cutoff is 5 or higher.

Screenshots

Application area

Where in the app is this happening?

• FrontEnd (please include route/section if possible)

Additional context
Can see original proposal where this came up here: https://app.daohaus.club/dao/0x64/0x046d1c324cd5ca0115e04ea1e4feecfaf44a8bf5/proposals/6

[plor]

Link is at the bottom, this has since been moved. Amount was:

PARAM2: wad
TYPE: uint256
VALUE: 8724462353742896000000

I believe it is there was about 8724462353742895500000 which is where the issue came from, since it seems to be rounding to 12 decimal places. I'm not sure if it matters that this was WXDAI.

[plor]

Trying to reproduce more, this proposal seemed to round up the 18th decimal place, resulting in a failing proposal.

https://app.daohaus.club/dao/0x4/0x3259342eed7cfa03fab8b0854fe6836a40bd1e93/proposals/10

[plor]

Related to #1773

[plor]

One solution suggested is to remove this button from the minion proposal flow.