Motion Photos: Option to convert to still photo

Current behavior:

Motion Photos always keep both the video clip and the still image, consuming more storage than a regular photo.

Problem:

• Users want to send/save just the still image without the motion component

• No built-in option to remove the video portion and keep only the photo

• Wastes storage space when Motion Photo isn't needed

Proposed solution:
Add an easy option to convert any Motion Photo to a standard still photo:

1. "Convert to still" button in photo view/edit

2. Extract and save only the keyframe as a regular photo

3. Optionally delete the original Motion Photo after conversion