refactor(posts): move post-processor projects under Posts/

Group the Cincinnati and GravographIS plugin projects in a Posts/
folder so new machine posts have one home. Project names, namespaces,
and the runtime Posts/ deploy target are unchanged; only relative
paths in the solution and project references move.

Posts/OpenNest.Posts.GravographIS/GravographISWriterOptions.cs

@@ -0,0 +1,24 @@
+namespace OpenNest.Posts.GravographIS
+{
+    public sealed class GravographISWriterOptions
+    {
+        public double DepthInches { get; set; } = 0.25;
+
+        public int FeedMmPerSec { get; set; } = 35;
+
+        // IS8000 work envelope in millimeters, from the operator-set upper-left
+        // work origin. Defaults to the catalog 0.610 m x 1.220 m bed. With an
+        // OpenNest quadrant-4 plate, motion is allowed right (+X) and down (-Y).
+        public double WorkEnvelopeXMm { get; set; } = 610.0;
+        public double WorkEnvelopeYMm { get; set; } = 1220.0;
+
+        // When true, the writer throws an InvalidOperationException naming the
+        // offending polyline and segment before any out-of-envelope record is
+        // emitted. Disable only for off-machine encoding tests.
+        public bool EnvelopeGuardEnabled { get; set; } = true;
+
+        // When true, lift at the end of the last cut and return to the
+        // operator-set origin before shutting the job down.
+        public bool ReturnToOriginAtEnd { get; set; } = true;
+    }
+}