refactor(mobile): AddActionButton

[idubnori]

Description

• Use MenuAnchor and BaseActionButton
  • Eliminate the need to calculate menu display positions
  • Bugfix: the existing menu may render in incorrect positions
• Style: Maintain consistent UI styling (details: ScreenShots section)

Note: these are based on #24175

Fixes # (issue)

• i do not know

How Has This Been Tested?

Manually tests on iOS Simulator

• ....

Screenshots (if appropriate)

Before	After	Ref. Google Photos

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.

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[immich-push-o-matic]

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