Reduce IMU pitch offset from -6° to -3° (was over-correcting)

-6° caused forward lean. Splitting the difference.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

gear_sonic_deploy/src/g1/g1_deploy_onnx_ref/include/input_interface/gamepad_manager.hpp

@@ -47,7 +47,7 @@
 #include "../localmotion_kplanner.hpp"  // For LocomotionMode enum
 
 /// Runtime-adjustable IMU pitch offset (degrees). Keys 9/0 to adjust via tmux.
-inline std::atomic<double> g_imu_pitch_offset_deg{-6.0};
+inline std::atomic<double> g_imu_pitch_offset_deg{-3.0};
 
 #if HAS_ROS2
 #include "ros2_input_handler.hpp"