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/hardware_full/matrix_radar_service.py

@@ -46,13 +46,31 @@ def create_matrix_radar_service(config: RunConfigModel) -> MatrixRadarService:
     if model == RunConfigModel.LIBREVNA_MULTI_MODEL:
         from python_app.hardware_full.multi_device_service import MultiDeviceLibreVnaService
 
-        return MultiDeviceLibreVnaService(
+        inner = MultiDeviceLibreVnaService(
             master_serial=config.radar.serial,
             slave_serials=list(config.radar.multi_device.slave_serials),
             force_external_reference=config.radar.multi_device.force_external_reference,
             recovery_attempts=config.radar.multi_device.recovery_attempts,
             backend_mode=config.radar.driver_mode,
         )
+        out_physical = config.matrix_output_switch_positions
+        in_physical = config.matrix_input_switch_positions
+        if out_physical <= 1 and in_physical <= 1:
+            return inner
+
+        from python_app.hardware_full.switched_matrix_radar_service import (
+            SwitchedMatrixRadarService,
+            build_physical_switch,
+        )
+
+        return SwitchedMatrixRadarService(
+            inner=inner,
+            output_switch=build_physical_switch(config.output_switch, out_physical, config.radar.driver_mode),
+            input_switch=build_physical_switch(config.input_switch, in_physical, config.radar.driver_mode),
+            inner_output_positions=RunConfigModel.MULTI_DEVICE_OUTPUT_POSITIONS,
+            inner_input_positions=RunConfigModel.MULTI_DEVICE_INPUT_POSITIONS,
+            settling_ms=config.runtime.settling_ms,
+        )
 
     if model == RunConfigModel.SN9000_MODEL:
         if config.radar.driver_mode != "native":