feat(posting): require verification and explicit risk acknowledgment

OpenNest.Core/IPostVerificationSupport.cs

@@ -0,0 +1,13 @@
+namespace OpenNest;
+
+/// <summary>
+/// Optional post contract for nest-level rapid verification. Opt in only when the
+/// post preserves Plate.Parts order and each placed Program's contour order and
+/// pierce positions. This does not certify retract height, parking or controller macros.
+/// Unknown/reordering posts still get nest diagnostics, but require acknowledgment
+/// that their final rapid sequence has not been verified.
+/// </summary>
+public interface IPostVerificationSupport
+{
+    bool PreservesPlacedProgramOrder { get; }
+}