Implements ROS2 adaptive PID gain scheduler for SaltyBot with:
- Subscribes to /saltybot/speed_scale for speed conditions
- Subscribes to /saltybot/terrain_roughness for surface conditions
- Adjusts PID gains dynamically:
* P gain increases with terrain roughness (better response on rough)
* D gain decreases at low speed (prevent oscillation when slow)
* I gain scales with both conditions for stability
- Publishes Float32MultiArray [Kp, Ki, Kd] on /saltybot/pid_gains
- Configurable scaling factors for each gain modulation
- Includes 18+ unit tests for gain scheduling logic
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
