[Feature Request] Add option to pin screenshot over apps

### **Use case :**
- Avoid opening two apps side by side for when you only need to see something from one of the opened apps and interact with the other one.
- Avoid scrolling back to check something when you're reading from a PDF file for example and there's a formula or graph somewhere which you are supposed to read its interpretation while still looking at it.

### **Options :**
- The pinned screenshot should be resizable when you drag its borders.
- The screenshot should be movable when you drag it.
- The feature should be optional for users who are not willing to grant overlay permission.

Start by reviewing the existing screenshot flow and Android overlay-permission handling. Define how a pinned screenshot is created, moved, resized, and dismissed, while keeping the feature optional for users who do not grant overlay permission. Done means the requested behavior works without disrupting the existing screenshot flow.

Written by the indexing model from the issue text.