Refine dead zone logic in PID controller

- Updated the handling of the dead zone in the PID controller to allow full signal response above the dead zone, improving control accuracy.
- Adjusted comments for clarity regarding the purpose of the dead zone in noise suppression.

Author: Abuudiii

lib/semian/pid_controller.rb

@@ -148,8 +148,8 @@ def calculate_p_value(current_error_rate)
           # Within dead zone: suppress noise
           delta_error = 0.0
         else
-          # Above dead zone: react to excess only
-          delta_error = raw_delta - dead_zone
+          # Above dead zone: full signal, dead zone only silences noise
+          delta_error = raw_delta
         end
 
         delta_error - (1 - delta_error) * @rejection_rate