Fix calculateInitialDueDate() to properly handle recurrence_weekdays array
when creating or updating weekly recurring tasks with multiple weekdays.
Previously, the function only checked for recurrence_weekday (singular) and
ignored recurrence_weekdays (plural array), causing tasks with multiple
weekdays to incorrectly get today's date instead of the next occurrence.
Changes:
- Add support for recurrence_weekdays array in calculateInitialDueDate()
- Fix buildUpdateAttributes() to pass recurrence_weekdays parameter
- Add 8 unit tests covering multiple weekdays scenarios
- Add 3 integration tests for API CREATE and UPDATE operations
- Maintain backward compatibility with single recurrence_weekday
The fix mirrors the proven logic from calculateWeeklyRecurrence() in
recurringTaskService.js and properly handles edge cases like unsorted
arrays, wrapping to next week, and JSON string parsing.
Fixes#974
65b9bbce39