feat: add 0xA9 feedforward frame and wire feedforward controller to motor output

- host 0xA9 frame → master_machine decode → robot_cmd publish
  via gimbal_feedforward topic → gimbal subscribe → yaw_motor.feed_input
- add DM_Feedforward_Controller_s with Kp and feed_input fields
- add feedforward term (Kp * feed_input) to motor control output
- add DM_Feedforward_Kp to motor init config

modules/master_machine/master_machine.c

@@ -62,6 +62,13 @@ static void DecodeVision()
         memcpy(&vision_data.motor_pitch_Kd,  p, 4);
         vision_data.debug_updated = 1;
     }
+    else if (sof == VISION_SOF_FEEDFORWARD && len == VISION_FEEDFORWARD_LEN)
+    {
+        if (calc_checksum(buf, VISION_FEEDFORWARD_LEN) != buf[VISION_FEEDFORWARD_LEN - 1])
+            return;
+        memcpy(&vision_data.feedforward, buf + 1, 4);
+        vision_data.feedforward_updated = 1;
+    }
     else if (sof == VISION_SOF_CMD && len == VISION_CMD_LEN)
     {
         if (calc_checksum(buf, VISION_CMD_LEN) != buf[VISION_CMD_LEN - 1])

modules/master_machine/master_machine.h

@@ -31,18 +31,24 @@
  *   [motor_pitch_Kp:4][motor_pitch_Ki:4][motor_pitch_Kd:4][checksum:1]
  *   全部 float, 依次为视觉环 yaw/pitch 和电机角度环 yaw/pitch 的 PID 参数
  *
+ * ---- 前馈输入帧 0xA9 (6 字节) ----
+ *   [SOF:0xA9][feedforward:4][checksum:1]
+ *   feedforward: float, 前馈输入值
+ *
  * checksum: 帧头到数据末尾前一字节累加和取低8位
  */
 
 #define VISION_SOF_AUTO    0xA5
 #define VISION_SOF_MANUAL  0xA6
 #define VISION_SOF_CMD     0xA7
-#define VISION_SOF_DEBUG   0xA8
+#define VISION_SOF_DEBUG       0xA8
+#define VISION_SOF_FEEDFORWARD 0xA9
 
-#define VISION_AUTO_LEN    18
-#define VISION_MANUAL_LEN  10
-#define VISION_CMD_LEN     3
-#define VISION_DEBUG_LEN   50
+#define VISION_AUTO_LEN         18
+#define VISION_MANUAL_LEN       10
+#define VISION_CMD_LEN          3
+#define VISION_DEBUG_LEN        50
+#define VISION_FEEDFORWARD_LEN  6
 
 /* 命令码 */
 #define VISION_CMD_SWITCH_AUTO   0x01
@@ -80,6 +86,10 @@ typedef struct
     float motor_pitch_Kp, motor_pitch_Ki, motor_pitch_Kd;
     uint8_t debug_updated;
 
+    /* 前馈输入 */
+    float feedforward;
+    uint8_t feedforward_updated;
+
     /* 命令 */
     uint8_t cmd;            // 最新命令码
     uint8_t cmd_pending;    // 有待处理命令标志