Synthetic regression fixture for #1266. Generated with ezdxf/Pillow from basic
geometry; it contains no external references or customer drawing content.

Layout1 has an INSERT of SyntheticImage at (2, 4). That block contains one
OLE2FRAME whose compound-file CONTENTS stream embeds a 64 x 32 BMP: red on
the left, blue on the right, with a green diagonal from top-left to bottom-right.
The frame occupies (0, 0) to (2, 1) in the block. Text and a triangle provide
vector controls for manually opening the fixture and checking Plot Preview.