connect_to_net and connect_passthrough previously only touched the
schematic: a wire stub plus a net label were added via
ConnectionManager, but the corresponding pad on the .kicad_pcb was
never updated.
pcbnew.SaveBoard() silently drops every net that is not referenced by
at least one board element (pad/track/via/zone). A net that exists
only in the schematic therefore disappears on save, and in KiCad the
board's ratsnest never shows anything.
Fix:
- new _assign_net_to_pad(component_ref, pin_name, net_name):
ensures the net exists on the board (creates NETINFO_ITEM if not)
and sets it on the matching pad of the matching footprint.
- _handle_connect_to_net calls it after the schematic op when
self.board is loaded.
- _handle_connect_passthrough parses ConnectionManager's 'connected'
entries ('J1/1 <-> J2/1 [PIN_1]') and assigns nets to both pads.
- register 'connect_to_net' in _BOARD_MUTATING_COMMANDS so the
existing auto-save path persists the pad assignment to disk.
3a172f0448