ControlAllocator: Periodically spin MC motors to shed ice (#26322)

This feature periodically spins the unused motors on VTOL airframes, to
break off ice that has built up in the motor while it is still feasible
to do so. Each ice shedding event sends a motor ouput of 0.01 to the
unused motors for 2 seconds.

Configured by `CA_ICE_PERIOD`, the duration of the entire cycle. Set to
0 to disable.

src/modules/control_allocator/module.yaml

@@ -605,6 +605,22 @@ parameters:
                 1: Remove first failed motor from effectiveness
             default: 0
 
+        CA_ICE_PERIOD:
+            description:
+                short: Ice shedding cycle period
+                long: |
+                    Ice shedding prevents ice buildup in VTOL aircraft motors by
+                    periodically spinning inactive rotors. When enabled (period
+                    > 0), every cycle lasts for the defined period and includes
+                    a 2‑second spin at 0.01 motor output. If period <= 0, the
+                    feature is disabled.
+            type: float
+            decimal: 1
+            unit: s
+            increment: 0.1
+            min: 0.0
+            default: 0.0
+
 # Mixer
 mixer:
     actuator_types: