fix(usage): exclude quota-less successes from retention

Preserve successful empty, credits-only, and unavailable-quota responses when their supplemental timestamp exceeds the quota retention window. Add cache and real-app expiry regressions. Update usage, development, and changelog documentation; configuration, translations, and TODO scope remain unchanged.
ee559259b3Simone committed on 9/9/2026, 9:19:48 AMparent2f459c3

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