Parametric Construction Points

[TheJoeFin]

PR Classification

New feature and UI enhancement for interactive parametric construction geometry in image measurement.

PR Summary

Introduces a full construction geometry system with interactive editing, edge detection, and integration into measurement and transform workflows. Adds robust serialization, undo/redo, and improved file handling.

• ConstructionGeometry, ConstructionOverlayControl, and related DTOs: Implements point/line/circle graph model, overlay control, and serialization logic.
• BoundaryProbeAnalyzer, ImageSampleBuffer: Adds color-aware edge detection for precise point placement.
• MainWindow and tool logic: Integrates construction tools, manages overlay lifecycle, tool state, and UI synchronization.
• GeometryMathHelper: Adds robust circumcircle solver for three points.
• File helpers: Improves image file writing with correct format and extension handling.

[TheJoeFin]

I found several correctness regressions that should be addressed before merging:

1. Valid quadrilaterals can become self-crossing (ConstructionOverlayControl.xaml.cs:343-366). NormalizeWinding produces a valid ring, but DetectedQuadrilateral reorders it using coordinate extrema. A valid trapezoid such as (0,0), (3,0), (1,1), (0,1) becomes a bow-tie, causing transform/un-warp markers to target the wrong corners.
2. Unrelated points can invalidate solved geometry (ConstructionSolver.cs:170-182). Boundary half-planes are oriented using the centroid of every construction point, including unattached and circle points. A stray point outside the polygon can flip those half-planes and change a valid construction to NoUsableCorners.
3. Edge dragging permits duplicate and self-loop lines (MainWindow.Construction.cs:408-413). Snapping the loose end does not perform the invariant checks used by the two-click and ghost-line paths, so it can reconnect to its starting point or create a second edge between an existing pair.
4. Point-drag undo is not finalized on mouse-up (MainWindow.xaml.cs:559-563, 2166-2200). EndDrag() only runs if a later mouse-move observes released buttons. Pressing Undo immediately after release can therefore target the previous operation.
5. Capture loss leaves construction gestures active (MainWindow.xaml.cs:342-350). The lost-capture handler only resets panning. Alt-tabbing during edge creation or boundary probing leaves temporary geometry and transaction state active.
6. Construction editing handles appear in exports (MainWindow.xaml.cs:1383-1433). Construction overlays are rendered with measurements, but their IsDragGizmoVisible state is not disabled like markup controls, allowing handles, candidates, and ghost lines into the output.
7. Undo can restore overlays from a previous image (UndoRedo.cs:674-684, MainWindow.xaml.cs:1689-1694). Opening another image removes construction controls without clearing the undo stack, so an old ConstructionOverlaysRemovedItem can reattach controls to the new image.
8. Boundary probing ignores alpha-only edges (ImageSampleBuffer.cs:22-23, 63-67). RGB sampling cannot distinguish transparent and opaque pixels with the same RGB values, including transparent borders produced by rotation.