Improve timer vibration

[DavisNT]

This is a super-simple fix for #391.
When timer ends the watch will vibrate until the side button is pressed or a sliding-down movement is made on the screen (maybe there are some more gestures).

[github-actions]

Build checks have not completed. Possible reasons for this are:

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2. The branch has conflicts
3. The firmware build has failed

[mark9064]

For reference: alternative to #1971