This PR fixes our page to screen conversion.
### Change Type
- [x] `patch` — Bug fix
### Test Plan
1. Drop an image onto the screen while the camera is panned and zoomed.
- [x] Unit Tests
Turns out there was one last terrible renaming PR to make. This PR
renames the `@tldraw.editor`'s `app` folder to `editor`. It should not
effect exports but it will be a gnarly diff.
### Change Type
- [x] `internal` — Any other changes that don't affect the published
package (will not publish a new version)
alex