domain/tetgen_worker: add worker script for TetGen subprocess execution

- Read a surface mesh and config (args/kwargs), run TetGen in a separate Python process, and persist nodes/elements to .npz.
- Provides a simple CLI for integration with tetrahedralize().

Author: zasexton

svv/domain/routines/tetgen_worker.py

@@ -0,0 +1,36 @@
+# tetgen_worker.py
+import sys
+import json
+import numpy as np
+import pyvista as pv
+import tetgen
+
+
+def main(surface_path: str, out_path: str, config_path: str):
+    # Load surface mesh
+    surface = pv.read(surface_path)
+
+    # Load tetrahedralize args/kwargs
+    with open(config_path, "r") as f:
+        cfg = json.load(f)
+
+    args = cfg.get("args", [])
+    kwargs = cfg.get("kwargs", {})
+
+    # Run TetGen
+    tgen = tetgen.TetGen(surface)
+    nodes, elems = tgen.tetrahedralize(*args, **kwargs)
+
+    # Save result
+    np.savez(out_path, nodes=nodes, elems=elems)
+
+
+if __name__ == "__main__":
+    if len(sys.argv) != 4:
+        print(
+            "Usage: python tetgen_worker.py <surface_path> <out_path> <config_path>",
+            file=sys.stderr,
+        )
+        sys.exit(1)
+
+    main(sys.argv[1], sys.argv[2], sys.argv[3])