Revert the implicit boxing pass: a bare `T` annotation is a raw value
again (`_U: U = new U(...)` fails with a pointer/value CastError), and
struct layouts are untouched.
`own T` is the explicit owned reference:
- resolves to one pointer layer (`Ptr(T)`); `own T?` stays nullable.
- a variable declared `own` is registered as an owned slot; a `new`
initializer is always taken over (outside the NLL frame-confined
predicate), so scope exit runs `__del__` + `free`.
- `new stack` is rejected for `own` (its storage dies with the frame).
- `own` bindings reject `None`; moves (`b: own T = a`) release the source
slot.
- a bare identifier named `own` still works as a name/type.
`Box[T]`, `RawT[T]`, `Option[T]` / `T?` stay available as explicit forms.
LSP completion lists `own`.
Probe: `struct U { ..., n: own U }` resolves and `U.__sizeof__()` = 24;
`_U: own U = new U(1,2,3,4); _B: own U = _U` runs and `print(_U.a)` fails
with LifetimeError; `own U = None`, `own U = new stack U(...)` fail fast;
without `own` the old CastError returns; `own` works outside OBS too.
Self-host 110/110; ListTest, GenericTest, GenericTest3, GenericTest4,
PtrOpProbe, HashLibTest, NewTest, NewLifetimeTest, StructTest and
EscapeOkTest pass.
TermiNexus
c37b8dc52c