feat: add adaptive isogrid tool — project foundations

- Python Brain: density field, constrained Delaunay triangulation,
  pocket profiles, profile assembly, validation modules
- NX Hands: skeleton scripts for geometry extraction, AFEM setup,
  per-iteration solve (require NX environment to develop)
- Atomizer integration: 15-param space definition, objective function
- Technical spec, README, sample test geometry, requirements.txt
- Architecture: Python Brain + NX Hands + Atomizer Manager

tools/adaptive-isogrid/src/nx/extract_geometry.py

@@ -0,0 +1,54 @@
+"""
+NXOpen script — Extract plate geometry from selected face.
+
+ONE-TIME: Run inside NX. User selects plate face, assigns hole weights.
+Exports geometry.json for the Python brain.
+
+NOTE: This is pseudocode / skeleton. Actual NXOpen API calls need
+NX environment to develop and test.
+"""
+
+# This script runs inside NX — NXOpen is available at runtime
+# import NXOpen
+# import json
+# import math
+
+
+def extract_plate_geometry(face, hole_weights):
+    """
+    Extract plate geometry from an NX face.
+    
+    Parameters
+    ----------
+    face : NXOpen.Face
+        The selected plate face.
+    hole_weights : dict
+        {loop_index: weight} from user input.
+    
+    Returns
+    -------
+    dict : geometry definition for export.
+    """
+    raise NotImplementedError(
+        "This script must be developed and tested inside NX Simcenter. "
+        "See docs/technical-spec.md Section 2 for full pseudocode."
+    )
+
+
+def sample_edge(edge, tolerance=0.1):
+    """Sample edge curve as polyline with given chord tolerance."""
+    # NXOpen: edge.GetCurve(), evaluate at intervals
+    raise NotImplementedError
+
+
+def fit_circle(points):
+    """Fit a circle to boundary points. Returns (center, diameter)."""
+    # Least-squares circle fit
+    raise NotImplementedError
+
+
+def export_geometry(geometry, filepath='geometry.json'):
+    """Export geometry dict to JSON."""
+    import json
+    with open(filepath, 'w') as f:
+        json.dump(geometry, f, indent=2)