[Bug]: Recurring task completion dates off by one day - timezone bug in v3.25

[EllenGYY]

Bug Description

What's the bug?

When marking recurring tasks as complete ("mark completed for this date") in normal note view / kanban view, the complete_instances array records yesterday's date instead of today's date, while normal task completedDate fields work correctly.

Steps to reproduce:

1. Create a recurring task (e.g., daily task with FREQ=DAILY)
2. Mark the task as complete, either direct click or using right click, "mark completed for this date", results are the same
3. Check the complete_instances array in the task's frontmatter
4. Observe that the date stored is yesterday's date instead of today's

Expected behavior:
The complete_instances array should contain today's date when marking a recurring task complete today, matching the behavior of completedDate for normal tasks.

Actual behavior:

• Normal tasks: completedDate shows the correct date ✓
• Recurring tasks: complete_instances shows yesterday's date ✗

Screen Recordings: (See the dateModified property with the actual correct time)
https://github.com/user-attachments/assets/bdbee3b2-eba5-4e85-8519-8ccf69078a3d

Additional context:
My timezone: US-East
Time when bug occurs: just past midnight

I am not sure if it is somehow related to this issue here #574

[EllenGYY]

After some testing, this only happens between midnight and 1 a.m. Highly possible that this is related to DST (daylight saving time) somehow.

[callumalpass]

Thanks very much for the detailed report here @EllenGYY . I'll look into a fix.