- Fix double timezone conversion in drag-and-drop that caused 4-hour time shifts
- Frontend now sends local times instead of UTC to backend for proper conversion
- Add missing timezone parameter to update_series method to fix recurring event updates
- Update both event modal and drag-and-drop paths to include timezone information
- Maintain RFC 5545 compliance with proper timezone conversion in backend
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
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