Allow inserting DD sequences with non-Cirq rules

[natestemen]

Summary

The DDD rule functions (e.g. xx, xyxy) are typed as returning QPROGRAM, and the public API (insert_ddd_sequences, execute_with_ddd, etc.) accepts Callable[[int], QPROGRAM]. However, the internal implementation of insert_ddd_sequences called Cirq-specific methods directly on the rule's return value, so any rule returning a non-Cirq circuit would fail at runtime:

from qiskit import QuantumCircuit
from mitiq.ddd.insertion import insert_ddd_sequences
from mitiq.interface.mitiq_qiskit import to_qiskit
from mitiq.ddd.rules import xx

def qiskit_xx(slack_length: int) -> QuantumCircuit:
    return to_qiskit(xx(slack_length))

qreg = QuantumCircuit(2)
qreg.h([0, 1])
qreg.id([0, 1])
qreg.id([0, 1])
qreg.h([0, 1])

# Raises AttributeError: 'QuantumCircuit' has no attribute 'transform_qubits'
insert_ddd_sequences(qreg, rule=qiskit_xx)

• Widen the rule parameter type from Callable[[int], Circuit] to Callable[[int], QPROGRAM] in insert_ddd_sequences / _insert_ddd_sequences
• Add an internal cirq_rule wrapper that converts the rule output to a Cirq Circuit (via convert_to_mitiq) and normalizes qubit indexing to LineQubits before the Cirq-specific DDD insertion logic runs

Test plan

• New test test_insert_sequences_with_qiskit_rule verifies a Qiskit-returning rule produces the same result as the equivalent Cirq rule
• All 170 existing DDD tests continue to pass

AI was used in helping create this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.40%. Comparing base (dd06bb2) to head (163d027).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3065   +/-   ##
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  Coverage   98.40%   98.40%           
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  Files         112      112           
  Lines        4940     4946    +6     
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+ Hits         4861     4867    +6     
  Misses         79       79           

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