The "Reset to deployed" toast action in resource/variable editors
called UserDraft.save with the backend value to repaint the form. That
left a duplicate-of-backend autosave in localStorage which would
silently restore on every subsequent reload, defeating the reset.
New UserDraft.discard(itemKind, path, fallback) clears LS AND resets
any live handle's in-memory state to the fallback, skipping the next
persist so the fallback doesn't round-trip back into storage. Backed
by a new `skipNextWriteOnce()` method on useLocalStorageValue's return.