- Add pgCorrectedModerationsTable to shared schema - Create backend corrections module (stats, list, create endpoints) - Add TunerPanel with Stats, History, and Submit sub-tabs - Add AuthOverlay gate for Tuner (admin-only, same as Live) - Set messages as default tab - Wire Tuner into sidebar, header, and mobile tab bar Co-Authored-By: Claude <noreply@anthropic.com>