forked from 1b-agent/opencadstudio-upstream
New ConstraintKind variants — Concentric, CenterPoint, Colinear, Midpoint, Fixed, PointOnCurve, EqualDistance, Symmetric — each built entirely from existing ocs_gcs (FreeCAD planegcs) primitives, no new solver math needed. build_constraint now returns Vec<Rc<dyn Constraint>> instead of Option<Rc<...>>, generalizing the old Coincident-only "needs a second system-level constraint" special case to every kind that needs one. Wired into the ribbon (7 new buttons), a new point+pre-selected-entity command for CenterPoint/Midpoint/PointOnCurve, a new 4-point command for EqualDistance, and the existing DWG-native class-name mapping (all 8 reuse the same generic "plain Geometrical node" path already built for Coincident/Horizontal/etc.). Deliberately not modeled: Normal and EqualCurvature, which for this app's Line/Circle-only entity model would just be Perpendicular and Equal wearing different DWG class names. Also makes DWG-native constraint persistence opt-in (Options > General, off by default) rather than unconditional: a scope that doesn't yet have the native graph is only given one when the setting is on, but a scope that already has one — from an earlier save, or a file that came from real AutoCAD — keeps getting it resynced regardless of the setting, so toggling it off never freezes a stale graph in place. Co-Authored-By: Claude Sonnet 5 <[email protected]>