refactor(brain): structured pocket output — 3 lines + 3 arcs per pocket

Replaced Shapely buffer-based fillet (59-pt polylines) with exact geometric
fillet computation. Each pocket now outputs:
- 3 straight edges (line start/end pairs)
- 3 fillet arcs (center, radius, tangent points, angles)

NX import updated to use SketchLineBuilder + SketchArcBuilder (3-point).
Total NX entities: ~2,600 (was ~13,000). Includes arc fallback to 2-line
segments if SketchArcBuilder fails.

Also outputs circular hole definitions for future NX circle creation.

tools/adaptive-isogrid/src/brain/__main__.py

@@ -89,8 +89,10 @@ def _plot_final_profile(geometry, pockets, ribbed_plate, out_path: Path) -> None
     ax.plot(np.r_[outer[:, 0], outer[0, 0]], np.r_[outer[:, 1], outer[0, 1]], "k-", lw=1.8, label="Outer boundary")
 
     for pocket in pockets:
-        pv = np.asarray(pocket["vertices"])
-        ax.fill(pv[:, 0], pv[:, 1], color="#88ccee", alpha=0.35, lw=0.0)
+        polyline = pocket.get("polyline", pocket.get("vertices", []))
+        pv = np.asarray(polyline)
+        if len(pv) >= 3:
+            ax.fill(pv[:, 0], pv[:, 1], color="#88ccee", alpha=0.35, lw=0.0)
 
     if ribbed_plate.geom_type == "Polygon":
         geoms = [ribbed_plate]
@@ -122,7 +124,7 @@ def run_pipeline(geometry_path: Path, params_path: Path | None, output_dir: Path
     ribbed_plate = assemble_profile(geometry, pockets, params)
     is_valid, checks = validate_profile(ribbed_plate, params)
 
-    profile_json = profile_to_json(ribbed_plate, params)
+    profile_json = profile_to_json(ribbed_plate, pockets, geometry, params)
     profile_json["checks"] = checks
     profile_json["pipeline"] = {
         "geometry_file": str(geometry_path),