024 stale view after take

// PIN: after `std/string:take(s)` consumes the <view!> binding `s` and
// produces a new <instance!> binding `owned`, the old binding `s` is stale.
// Using `s` in a subsequent call is use-after-discharge: the view! obligation
// was consumed by take, and `s` no longer has a valid phantom state.
//
// The transition take: *String<!view> → | instance *String<instance!>
// is the ATS/Mezzo "transfer" move: ownership moves to a new name.
// The old name is invalid from that point forward.
//
// Grounding:
//   - take consuming <!view>:    koru_std/string.kz:74
//   - take producing instance!:  koru_std/string.kz:75
//   - from-page/take flow shape: 610_002_string_ownership/input.kz:5-11
//   - use-after-discharge shape: 610_005_reject_use_after_free/input.kz:6 (free then len)
import std/string

std/string:from-page(text: "hello")
| ok s |> std/string:take(s): owned |> std/string:len(s): _ |> std/string:free(s: owned)
| err _ |> _