Add MultiTurnStrategy support to Qiskit code validation example

[vabarbosa]

Description

The Qiskit code validation example (docs/examples/instruct_validate_repair/qiskit_code_validation/) currently only supports RepairTemplateStrategy for the Instruct-Validate-Repair (IVR) pattern. The Future Work section mentions adding MultiTurnStrategy integration to compare and showcase different repair strategies.

Proposed Solution

Implement configurable strategy selection in the example to support both RepairTemplateStrategy and MultiTurnStrategy, allowing users to choose between strategies via a simple flag. In addition, be able to compare and better understand which strategy works best for their use case.

Expected Benefits

1. User flexibility: Users can experiment with both repair strategies
2. Educational value: Demonstrates IVR pattern effectiveness
3. Completeness: Addresses the MultiTurnStrategy integration from Future Work

Additional Context

This enhancement will help users understand:

• How different repair strategies handle validation failures
• Which strategy performs better for their use case
• The effectiveness of the repair loop

Related

• Future Work item: "MultiTurnStrategy Integration" in docs/examples/instruct_validate_repair/qiskit_code_validation/README.md
• Sampling Strategies documentation: docs/examples/instruct_validate_repair/README.md#sampling-strategies
• docs: add Qiskit code validation IVR example #576 (comment)
• MultiTurnStrategy doesn't include validation failure reasons in repair messages #631