✨ Support array-valued OpenQASM outputs

[simon1hofmann]

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Problem Statement

The classical-array work in #2109 supports internal storage, but array-valued
OpenQASM outputs remain unsupported. Users must currently copy selected elements
into scalar outputs. An output array must retain its shape, element type, and
values after the entry function returns; returning the current stack-backed
memref.alloca storage would leave a dangling reference.

This gap was deliberately deferred until after #2546, which changes computed
output handling and recording.

Proposed Solution

Support array-valued output declarations using a defined value or ownership
contract shared by the frontend and its consumers.

• Define the lifetime and ownership of returned arrays, including empty and
  multidimensional arrays, without exposing expired stack storage.
• Preserve output shape, element type, order, and integer/angle representation
  through QC/QCO conversion and supported serialization paths.
• Extend native result handling and QIR output recording consistently with the
  computed-output contract established by ✨ Preserve structured compilation and execution #2546. Diagnose output element types
  or target profiles that cannot be represented.
• Test mutable arrays, aliased views, output snapshots, empty dimensions,
  repeated calls, and rejection of uninitialized output elements.

Acceptance: a program can return a fully initialized array and retrieve the
same typed, shaped values through each supported execution/export path, without
dangling storage, silent truncation, or changed scalar-output behavior.

Follow-up to #2109; depends on #2546. Classical subroutines and array-reference
parameters are separate work, not prerequisites for standalone array outputs.