Fix overlay scope handling for strict scope healing

[AlexanderOnischenko]

Summary

• stamp overlay entries with the overlay run’s scope, tag, run id, and timestamp rather than the current selection’s metadata
• enforce strict-scope history by ignoring overlay PASS healing when scope mismatches while still reporting new failures
• expand explain output and add regression tests covering strict-scope overlay healing behavior

Testing

• ruff check examples/demo_qa/batch.py tests/test_demo_qa_batch.py
• python -m pytest tests/test_demo_qa_batch.py::test_only_failed_strict_scope_ignores_overlay_pass tests/test_demo_qa_batch.py::test_only_failed_strict_scope_allows_overlay_pass_when_scope_matches tests/test_demo_qa_batch.py::test_only_failed_explain_notes_scope_mismatch

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Codex Task

[AlexanderOnischenko]

@codex, please review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Bravo.

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