Fix barrier unrolling to preserve multi-qubit barrier statements

[ryanhill1]

Summary

• Barriers now unroll as a single multi-qubit statement (e.g. barrier q[0], q[1], q[2]) instead of splitting into individual per-qubit barriers
• Fixed physical qubit handling in the barrier consolidation path to iterate over all qubits instead of only the first

Summary by CodeRabbit

• Bug Fixes
  • Barrier handling now preserves multi-qubit barrier statements as single directives (including ranges and mixed qubit specs) instead of splitting them into per-qubit barriers.
• Tests
  • Updated and added tests to expect consolidated multi-qubit barrier output across QASM2/QASM3, device-qubit mapping, range unrolling, and visualization rendering.