fix: set duration to null when not present

[meesfrensel]

Description

Currently, duration is either null or '00:00:00.000' depending on which api endpoint you use. For example GET /assets/{id} returns a non-null string while GET /timeline/bucket 's duration can be nullable.

How Has This Been Tested?

Standard test suite + manually inspecting api responses.

API Changes

The AssetResponseDto dto used in many places now has nullable duration.

Checklist:

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if applicable
• I have no unrelated changes in the PR.
• I have confirmed that any new dependencies are strictly necessary.
• I have written tests for new code (if applicable)
• I have followed naming conventions/patterns in the surrounding code
• All code in src/services/ uses repositories implementations for database calls, filesystem operations, etc.
• All code in src/repositories/ is pretty basic/simple and does not have any immich specific logic (that belongs in src/services/)

Please describe to which degree, if any, an LLM was used in creating this pull request.

None

[immich-push-o-matic]

Label error. Requires exactly 1 of: changelog:.*. Found: 📱mobile, 🖥️web, 🗄️server. A maintainer will add the required label.

[mertalev]

I agree with using null instead, but this is a breaking change, right? We'd need to leave this for the eventual 3.0.

[meesfrensel]

I think you're right, would be a breaking change for api/sdk users. Hmm that's really annoying, since it's supposed to remove the need for these dumb !includes(00:00:00.000) checks, not break anyones workflow 😅

If you decide it's definitely a breaking v3.0 change, let me know if you want to keep the pr open or not!

[danieldietzler]

This is definitely a breaking change, since the API contract (duration is not nullable) has been broken. I would personally say it's fine to keep this around for the time being