Activity_Diary: a diary entry from last month is labelled "YESTERDAY" in the history list

[fubai578]

• I can reproduce the bug with the latest version from the official source.
• I searched open and closed issues for the same symptom.
• I checked the FAQs inside the app and the problem is not listed.
• I filled in all required details.
• This report contains only one bug.

Steps to reproduce

1. Start the app and select the built-in Cinema activity.
2. Open the navigation drawer, select Diary, and tap the current Cinema history row to open the editor.
3. Change Start date to 11 August 2026, which is in the previous month, and tap OK.
4. Change End date to 11 August 2026 as well and tap OK.
5. Tap Save in the top right corner.
6. Look at the Diary list after returning: check which date group the entry is placed under.

Expected behavior

The entry is dated 11 August, so it should be grouped under a label that matches its real date,
for example a date label such as "11 August 2026". The list should not show a relative date label
that contradicts the saved date.

Actual behavior

After saving, the entry itself shows "Start: 2026.08.11 14:56" and "End: 2026.08.11 14:57", so the
date is correct. However it is placed under a group titled "YESTERDAY", while the other entries for
the current day are grouped under "TODAY". The date on the entry and the label of the group it sits
in contradict each other, and 11 August is more than a month in the past, so "yesterday" does not
match it at all.

Screenshots / screen recordings

Environment

• App version: 1.4.2 (version code 136)
• Android: Android 14 (API 34)
• Device: Android emulator, Pixel 6 profile (1080 x 2400)

Additional information

Package: de.rampro.activitydiary
Version: 1.4.2.

Entries from today are grouped under "TODAY" correctly, so the relative dates themselves work; this only goes wrong for entries around a month boundary.

Seeing "Yesterday" next to a date that says the 11th made me think the entry had been recorded on the wrong day.