Bug: Offset while using brush tool on iPad

### Description

- Large offset while using the web version on iPad.
- Using the apple pencil to draw with the brush tool on the iPad surface, there is a large noticable offset of the ink appearing from the tip of the pencil touching the screen.
- The brush ink also flows outside of the artboard (although I suspect this might be by desgin)

### Video Demonstration
https://drive.google.com/file/d/1buYIvX035Be9K-pn0Rn7eCGvYZ4jJTX1/view?usp=sharing

### Other details

- Safari version: 26
- iOS version: iPadOS 26.0
- iPad model: iPad Pro 13 inch, 2024

### Preliminary thoughts

- The mismatch is CSS px vs device px and/or origin differences.
look at https://github.com/GraphiteEditor/Graphite/blob/master/editor/src/messages/tool/tool_messages/brush_tool.rs