Spice Simulation

Add a small ngspice-backed testbench to a .zen design.

Workflow

1. Confirm the target is simulation-capable by running a dummy sim. pcb sim <path/to/file.zen> --setup "* empty setup check"

2. If the SPICE model is missing, add it. Find a vendor model, download it, or create a simple behavioral model if needed. Wire it through the leaf component with spice_model=SpiceModel(...) before writing the testbench.

3. Create a focused testbench file. Use a generic package-local path such as <package>/testbench/test_<scenario>.zen.