feat(astra): add independent nesting engine and fix hole validation

Replace the Terra scaffold with an independent configuration-space contact placer and bounded stock-plan search. Include plugin tests, synthetic and DXF benchmark drivers, results, and deployment documentation.

Correct shared collision clipping and hole subtraction so curved-hole inserts validate consistently. Cover translated layouts, spacing violations, operand order, winding, and independent boolean-area comparisons.

Validation: 1,293 tests passed with 12 fixture skips; all 34 synthetic/generated and four DXF cases are valid and complete.

OpenNest.Tests/Geometry/CollisionTests.cs

@@ -120,9 +120,8 @@ public class CollisionTests
 
         var result = Collision.Check(a, b, holesA: holeA);
 
-        // Hole subtraction uses a conservative approach (keeps partial overlaps),
-        // so we only verify that a collision is still detected for solid material.
         Assert.True(result.Overlaps);
+        Assert.Equal(3, result.OverlapArea, 6);
     }
 
     /// <summary>