_build_connectivity() used sch.list_component_pins() which returns
empty for custom library symbols. Added a second pass that falls back
to parse_lib_symbol_pins() + transform_pin_to_schematic() for any
component that returned 0 pins from the API. This brings custom IC
pins (e.g. ESP32-P4's 105 pins) into the union-find net graph.
Ryan Malloy
b347679c67