docs: remove pre-IVR validation and update readme with v2 benchmark results

[ajbozarth]

Misc PR

Type of PR

• Bug Fix
• New Feature
• Documentation
• Other

Description

• Link to Issue: Fixes

Updates the qiskit_code_validation example and its README based on a re-benchmarking run after removing the pre-IVR input validation from the example. Previously, the example ran a pre-condition validation on the input code before entering the IVR loop, which made the repair loop mostly unnecessary. This PR removes that pre-validation so the IVR loop handles all validation end-to-end, and updates the README to reflect the corrected pipeline description and new benchmark numbers.

Changes:

• Remove pre-IVR input validation from generate_validated_qiskit_code() — IVR now handles all validation
• Update README: IVR pipeline steps, strategy performance table (new numbers from v2 benchmark), expected output, and "What This Example Does" description

Testing

• Tests added to the respective file if code was changed
• New code has 100% coverage if code was added
• Ensure existing tests and github automation passes (a maintainer will kick off the github automation when the rest of the PR is populated)

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[ajbozarth]

cc @vabarbosa

new benchmark analysis can be seen at https://github.com/ajbozarth/toolbox/blob/main/mellea/qiskit_code_validation/benchmarking/run_ivr_20260331_183642/analysis_v2.md

[vabarbosa]

LGTM