fix(arm): also negate motor direction for reversed J1 motor

Previous +290 fix handled static position mapping but motion direction was still reversed. Correct formula: motor = -height - 290. This handles both: position endpoints (height -290/-0 maps correctly) AND motion direction (increasing height now moves arm up instead of down).

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

ros2/src/udp_teleop/udp_teleop/arm_control.py

@@ -128,7 +128,7 @@ class ArmJointState:
     def to_udp_message(self) -> bytes:
         """转换为 UDP 消息"""
         return (
-            f"JXB:{self.height + 290}:{self.j2}:{self.j3}:{self.j4}:"
+            f"JXB:{-self.height - 290}:{self.j2}:{self.j3}:{self.j4}:"
             f"{self.j5}:{self.j6}:0:0:EZHY\n"
         ).encode("utf-8")
 

ros2/src/udp_teleop/udp_teleop/keyboard_control.py

@@ -310,7 +310,7 @@ class KeyboardUdpControlNode(Node):
     def build_arm_cmd(self):
         joints = self.arm_joints
         return (
-            f"JXB:{self.arm_height + 290}:"
+            f"JXB:{-self.arm_height - 290}:"
             f"{joints[0]}:{joints[1]}:{joints[2]}:"
             f"{joints[3]}:{joints[4]}:0:0:EZHY\n"
         ).encode()