fix: handle PDK_ROOT being unset for volare

project.py

@@ -549,7 +549,7 @@ def harden(self):
  )
  open("runs/wokwi/PDK_SOURCES", "w").write(pdk_sources)
  volare.enable(
- os.environ["PDK_ROOT"],
+ volare.get_volare_home(), # uses PDK_ROOT if set, ~/.volare otherwise
  {"sky130A": "sky130"}[config["PDK"]],
  pdk_sources.split()[1],
  )