`comment_add` converted a note's or attachment's `at` (the icon's top-left
as displayed) as a single point through `PageInfo::view_to_user`, and the
engine's `rect_for` extends the icon square from `at` toward +x/-y in user
space. On an unrotated page the displayed and user-space top-left are the
same corner; under `/Rotate` they are different corners of the square, so
the icon landed one icon width (20 pt) away from the requested point.
`icon_anchor` converts the whole displayed square to user space and takes
its user-space top-left, so the `/Rect` covers the requested square under
any rotation. `PageInfo::view_rect_to_user` is the render-side counterpart
of `view_rect_to_quad`, and `NOTE_SIZE` is re-exported from the engine.
Test: `note_icons_anchor_at_the_requested_corner_on_rotated_pages` adds a
note and an attachment on pages rotated 0/90/180/270 and asserts the
`comment_list` rectangles; before the fix the 90° page reports
[52, 72, 72, 92] for a note asked for at [72, 72].
Co-authored-by: wstock <1394687+wstock@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>