feat: Add Effect set_unbreakable.

[CallumJohnson]

Minimal - make the holder item unbreakable while the effect is active

effects:
  - id: set_unbreakable

Full example with all options shown explicitly

effects:
  - id: set_unbreakable
    args:
      value: true               # true = unbreakable, false = remove the flag
      slot: holder              # target the item that provides this effect
      persist_on_disable: true  # keep unbreakable after the effect turns off

Make the player's helmet unbreakable while holding the item

effects:
  - id: set_unbreakable
    args:
      slot: helmet

Temporarily make mainhand unbreakable on trigger, then revert when disabled

effects:
  - id: set_unbreakable
    args:
      slot: mainhand
      persist_on_disable: false  # removes unbreakable flag when effect ends

Remove the unbreakable flag from the holder item

effects:
  - id: set_unbreakable
    args:
      value: false

[Exanthiax]

Great!