Fix total iteration reporting for warm-up loop

[Suke0811]

Summary

• include the warm-up iteration when calculating total iterations in reports
• treat stored initial_duration as evidence of recorded work when building reports
• add regression test to ensure warm-up iterations are counted in report results

Testing

• PYTHONPATH=. pytest tests/test_ratecontrol.py::test_spin_sync_report_counts_warmup_iteration

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Codex Task