Improve UI of budget inputs

[chelseaSchmidt]

• Discard type="number" because it makes the input buggy as hell - instead, manually allow only a number between 0 and 999 in the onChange

• Add placeholder text

• Make background white so it pops more

• Add a mini stepper to improve UX on a phone

• Mask value of 0 with an empty string to prevent leading 0s. Ended up not getting into a .touched analysis - UX isn't as bad as I feared:

  • Typing a single zero appears to do nothing - fine
  • Using the stepper to decrement from 1 appears to empty the input - fine
  • Typing 100 and then deleting the leading 1 is the oddest - this also empties the input. I'm okay with it though