fix(mobile): prevent live photo from getting stuck during dismiss animation

[LeLunZ]

Description

This PR fixes an issue where a Live Photo would get stuck in the close animation, if a user tried to dismiss the asset viewer, and the Live Photo stops playing in the animation.

This happens because _buildPhotoView rebuilds mid animation and switches from PhotoView.customChild to PhotoView.

FIX: we "freeze" the live photo. Which means if it's currently playing we don't switch away from the video viewer (photo viewer custom child) till the animation finishes.

Fixes #27710

How Has This Been Tested?

• iOS/android simulator

Checklist:

• I have carefully read CONTRIBUTING.md
• 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.

Claude did most of the implementation, with my guidance on what to implement. I gave it specific instructions on what to change. I reviewed the code and fixed issues I found.