[3.0.0] Add option to define a fixed timezone (like in Apple Calendar)

I came back to Thailand from Japan on Feb 29 and open app to check on Mar 1 and found that all transactions on last month shift -1 day. also I found that transactions that I input set date to 31 Jan become 30 Jan

updated:

I tried to change timezone back to Japan which is faster than Thailand only 2 hours the date become correct but I only set only date on transaction not time should it not be cause different date when I change timezone?

Result of Fabian’s analysis:

This approach is technically correct, but I understand how it might seem confusing at first glance. To address this, there are a couple of potential solutions similar to what Apple offers in its calendar app (see this article):

1. Save the time zone for each transaction: This would allow transactions to always display in the time zone in which they were recorded. However, this could lead to different transactions appearing in different time zones, which might also be confusing.

2. Introduce a global time zone setting: This would allow all transactions to display consistently in one selected time zone.

   => Option 2 seems to be the best way to implement this feature, as it would prevent transactions from being shifted. The user will be able to define a fixed time zone in the app's advanced settings. To visualize the time zone difference, the time zone will be displayed next to the timestamp in the date selection cell if it differs from the user's current local zone. For example, it might display as 12.08.2025 – 8:00 AM (EST).