Preserve releases on discarded qubit allocations

[Ian Davis (idavis)]

Issue

The HIR qubit-allocation rewrite assumed that single-qubit and qubit-array allocations always used a named binding. Valid code such as use _ = Qubit(); or use _ = Qubit[2]; therefore triggered a compiler panic.

Discarding the source-level binding does not remove the allocation's lifetime: the compiler must retain a reference so it can release the qubits when their scope ends, including on early exits.

Fix

• Generate a hidden local for discarded scalar and array allocations.
• Register that local with the existing cleanup machinery, preserving normal scope-exit and early-return releases.
• Leave named bindings and tuple-allocation behavior unchanged.