A tuple/list literal on the right of a multi-target assignment used to
return no value (`assignment rhs is None ... [kind=51]`). It is now
staged and assigned target by target:
- every RHS element is evaluated left to right and parked in its own
temporary slot, so a swap always reads the old values;
- each target is then written by the ordinary single-target path, which
keeps const checks, coercion, attribute/field stores, array and list
element stores (`__setitem__`) and ownership handling unchanged;
- the temporary's life tag is copied from the staged expression, so
pointer assignments keep their existing frame/heap lifetime;
- starred elements/targets and compiler-owned `new ... slife` objects
fail fast (they cannot be staged without changing their semantics).
Probe: ints, array elements (`a[i], a[i+1] = a[i+1], a[i]`) and struct
fields (`p.x, p.y = p.y, p.x`) all swap correctly (exit 2304);
self-host 110/110; PtrOpProbe, HashLibTest, GenericTest3 and ListTest
still pass.
TermiNexus
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