SQLBI Whiteboard 1.7.1 (dev 3419)

Import objects from older Microsoft Whiteboard boards (1.7.1) (#172)

Boards made with older versions of Microsoft Whiteboard hold three
object types that 1.7.0 did not read, so the import listed them as left
out after the import. Five of six teaching boards exported on 29
September showed the message.

| Type | What the page holds | Becomes |
| --- | --- | --- |
| `AzureImage` | A picture written as a `FluidImage` is, with the data
URI labelled `image/*` | A picture, as any other |
| `LegacyEllipse` | An SVG `ellipse` centered on the anchor, outline in
`stroke`, width and fill in the style | An oval |
| `LegacyPolygon` | An SVG `polygon` whose points start at the anchor |
The shape kind its corners have (every sample is a rectangle) |

An ellipse's radii can differ from its SVG box, in proportion as well as
in size. Edge draws the radii, and they are what line up with the ink
around the Venn diagrams, so the importer uses them.

Large rectangles come in with rounded corners, because the board has no
square-cornered rectangle. This is already listed as a limitation in
`docs/microsoft-whiteboard-import.md`.

Verified by opening all six boards in the application: nothing is left
out, and the ellipses, rectangles, and pictures sit in place against the
ink. A third synthetic page in the Core smoke tests covers the three
types. The solution builds clean and both smoke test harnesses pass.

The version goes to 1.7.1, with a CHANGELOG entry.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>