`path_as_rect` in the vendored hayro-interpret took any five-element path whose
points reached all four corners of its bounding box for that box. An open
polyline of one MoveTo and four LineTo passes that test when its ends sit on
the corners, so it was drawn as a closed rectangle and a clip of that shape was
dropped. VectorCraft #2920: an open zigzag in an .ai file opened as its
bounding box.
Port PdfCraft #3327 (hayro-interpret patch 35): a path is a rectangle only when
its four points are distinct, each step runs along one axis, and the last point
returns exactly to the first, closed with ClosePath or a fourth line.
Tests: `rectangles` in crates/pdf/tests/interpretation.rs (4 of its 5 tests
fail without the change) and `context::path_as_rect_tests` in the vendored
crate. SOURCE.json and the reader ledger record the change.
Don Omondi