Add get_hull convenience wrapper around run_regionchooser

src/simstadt/runner.py

@@ -229,7 +229,9 @@ def run_simstadt(workflow_path: Path, name: str) -> str:
         return result.stdout
 
 
-# TODO: Add get_hull
+def get_hull(citygml_path: str | Path) -> str:
+    """Return the hull of a CityGML file as a WKT string."""
+    return run_regionchooser("--get-hull", f"--input={Path(citygml_path).as_posix()}")
 
 
 def run_regionchooser(*params: str) -> str: