feat: date pick question

[ibrahimozkn]

This pull request introduces support for a new DateQuestion type in the questionnaire system, including backend model, serialization, designer form controls, and frontend UI integration. The changes enable date and date-time questions with validation, customizable formats, and localization. The most important changes are grouped below:

Backend Model & Serialization:

• Added the new DateQuestion model with fields for minimum/maximum date, format presets, and initial value, including JSON serialization and deserialization (date_question.dart, date_question.g.dart, date_format_preset.dart). [1] [2] [3]
• Registered DateQuestion in the questionnaire question factory and exported it in the questions module (question.dart, questions.dart). [1] [2]

Designer Form Integration:

• Added form controls and validation helpers for date questions in the designer, including controls for min/max/initial date and format preset, and auto-correction logic for initial value outside range (question_form_controller.dart). [1] [2] [3] [4]

Frontend UI Integration:

• Implemented the DateQuestionWidget for the app, supporting date and time picking, validation, formatting, clearing, and submission, with localization support (date_question_widget.dart, question_container.dart). [1] [2] [3]

Localization:

• Added new localization keys and translations for date picker UI and validation messages in English and German, and updated the localization interface (app_en.arb, app_localizations.dart, app_localizations_en.dart, app_localizations_de.dart). [1] [2] [3] [4]

Miscellaneous:

• Minor import and type registration updates to support the new question type and designer integration (question_form_controller.dart).

These changes collectively enable robust date and date-time questions in both the study designer and participant app, with full localization and validation support.

[github-actions]

Visit the preview URL for this PR (updated for commit 911ce56):

• https://studyu-dev-app--pr796-feat-date-question-xxvlgzfm.web.app
• https://studyu-dev-designer--pr796-feat-date-question-5io1vodo.web.app

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[johannesvedder]

"Invalid" question does not get saved on the server.

[johannesvedder]

The validation message is directly printed when the question is shown. I don't think we need it or only show it for invalid entries?

[johannesvedder]

Bug 2 from above is still happening

[johannesvedder]

[johannesvedder]

And what effect does the submit button has? Do you need to press it or is it unnecessary cause the state seems to update itself for first entry and later entry even if the button is not pressed, so I think it can be deleted?

[johannesvedder]

See above

[johannesvedder]

The following bug is still present:

• You should not be able to submit a questionnaire if not all time/date fields have been filled out

[johannesvedder]

Failing E2E test also needs to be fixed

[johannesvedder]

I will wait with this until #844 is merged