Fix timezone handling for recurring events

[sKawashima]

Summary

• Fix timezone conversion issues in recurring event processing that caused incorrect date filtering
• Improve applyRecurrenceDateAndTimezone function to handle timezone offsets correctly
• Update date range comparison logic to use timezone-aware calculations

Problem

When running in non-UTC timezones (e.g., JST UTC+9), recurring events scheduled after 15:00 would incorrectly display events from the previous day due to improper timezone handling in the recurrence calculation logic.

Solution

1. Modified applyRecurrenceDateAndTimezone to properly handle UTC recurrence dates and convert them to the correct timezone while preserving the original event time
2. Updated processRecurringRules to use UTC for rrule calculations and timezone-aware date comparison
3. Fixed date filtering logic to correctly identify events within the requested date range

Test plan

• Test recurring events in JST timezone (UTC+9)
• Verify events after 15:00 show correct day's events
• Confirm timezone conversion preserves original event times
• Build and verify no compilation errors

[muness]

Thanks for the fix and the readability improvements!

[muness]

I apologize for the delay, just pushed in 1.10.1