Add real switch support for multi-device matrix radar

MultiDeviceLibreVnaService only exposes the 2x4 virtual combo matrix on
its own USB transport. When a physical GPIO switch sits on the master
stimulus and/or slave receiver path, the effective matrix is wider than
that. SwitchedMatrixRadarService wraps the inner service and drives the
extra switch(es) between acquire_collection calls, widening the combo
matrix by the physical position counts (matrix_output_switch_positions /
matrix_input_switch_positions in RunConfigModel).

Combo-matrix construction was centralized into
RunConfigModel.build_runtime_combos() so the GUI, workflows, and codec
all derive the same widened matrix instead of each computing its own
version of the virtual 2x4 layout.

python_app/gui/controllers/app_window_config/profile_io_mixin.py

@@ -61,7 +61,7 @@ class AppWindowConfigProfileIOMixin:
         """Return the canonical virtual combo matrix shown for matrix-mode radars."""
         return ",".join(
             f"{int(combo.input)}:{int(combo.output)}"
-            for combo in RunConfigModel.build_matrix_radar_virtual_combos()
+            for combo in self._defaults_config.build_runtime_combos()
         )
 
     def _sync_pass_through_y_controls(self) -> None:

python_app/gui/controllers/app_window_config/state_builders.py

@@ -125,7 +125,7 @@ class AppWindowConfigStateBuildersMixin:
         if config.is_matrix_radar:
             return ",".join(
                 f"{int(combo.input)}:{int(combo.output)}"
-                for combo in RunConfigModel.build_matrix_radar_virtual_combos()
+                for combo in config.build_runtime_combos()
             )
         combos = list(config.combos)
         full_combos = config.build_full_combos(config.input_switch.positions, config.output_switch.positions)