fix(extract): increase chord tolerance to 1mm, cap at 500 pts/edge

0.1mm was generating thousands of unnecessary points on straight
edges. Now: 1mm default, 0.5mm minimum, 500 max per edge.
Curves still get proper sampling, straight edges stay lean.

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

@@ -156,10 +156,12 @@ def _sample_edge_polyline(edge: Any, chord_tol_mm: float, lister: Any = None) ->
     except Exception:
         length = _norm(_sub(p2, p1)) if not is_closed else 50.0
 
-    tol = max(float(chord_tol_mm), 0.01)
+    tol = max(float(chord_tol_mm), 0.5)  # 0.5mm chord tolerance — good balance
     n_pts = max(8, int(math.ceil(length / tol)))
     if is_circular or is_closed:
         n_pts = max(24, n_pts)
+    # Cap to avoid absurd point counts on long straight edges
+    n_pts = min(n_pts, 500)
 
     if is_linear and not is_closed:
         return [p1, p2]
@@ -377,7 +379,7 @@ def _chain_edges_into_loops(
     edges: List[Any],
     lister: Any = None,
     tol: float = 0.01,
-    chord_tol_mm: float = 0.1,
+    chord_tol_mm: float = 1.0,
 ) -> List[Tuple[bool, List[Point3D]]]:
     """
     Chain edges into closed loops by matching vertex endpoints.
@@ -747,7 +749,7 @@ def extract_sandbox_geometry(
     body: Any,
     sandbox_id: str,
     lister: Any,
-    chord_tol_mm: float = 0.1,
+    chord_tol_mm: float = 1.0,
 ) -> Dict[str, Any]:
     """
     Extract a sandbox face into a JSON-serializable dict.
@@ -859,7 +861,7 @@ def main():
                 body=body,
                 sandbox_id=sandbox_id,
                 lister=lister,
-                chord_tol_mm=0.1,
+                chord_tol_mm=1.0,
             )
 
             out_path = os.path.join(output_dir, f"geometry_{sandbox_id}.json")