test: improve speed by removing date-fns barrel imports #2996

Job	Run time
Prepare CI	5s
Lint App / biomejs	21s
Tests / Run Tests	1m 50s
Tests / SonarQube Cloud Analysis	1m 22s
Build / Build Windows (electron-builder)	2m 5s
Build / Build Linux (electron-builder)	3m 26s
Build / Build macOS (electron-builder)	2m 58s
	12m 7s

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