fix(arm): compensate for reversed J1 motor direction

J1 motor rotation is reversed after replacement: code height=0 now maps to physical bottom (was -290). Fix by adding +290 offset in UDP command (to_udp_message and keyboard_control). User-facing coordinate system (-290=bottom, 0=top) is unchanged; FK/IK/state tracking unaffected.

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}:{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}:"
+            f"JXB:{self.arm_height + 290}:"
             f"{joints[0]}:{joints[1]}:{joints[2]}:"
             f"{joints[3]}:{joints[4]}:0:0:EZHY\n"
         ).encode()