docs: 补充代码注释，增强代码可读性

src/line_laser_modbus/__init__.py

@@ -5,6 +5,7 @@ from line_laser_modbus.config import AppConfig, PollingConfig, SerialConfig
 from line_laser_modbus.models import DeviceSnapshot, DeviceStatus, ModeCommand, Pose6D
 from line_laser_modbus.runner import PollingRunner
 
+# 公开库调用时最常用的类型和入口。
 __all__ = [
     "AppConfig",
     "DeviceSnapshot",

src/line_laser_modbus/constants.py

@@ -1,10 +1,12 @@
 """来自 docs/proto.md 的协议常量"""
 
+# 固定从站地址和功能码。
 SLAVE_ID = 0x08
 
 FUNC_READ_HOLDING_REGISTERS = 0x03
 FUNC_WRITE_MULTIPLE_REGISTERS = 0x10
 
+# 保持寄存器绝对地址。
 ADDR_MODE_COMMAND = 0xD000
 ADDR_DEVICE_STATUS = 0xD001
 ADDR_CURRENT_POSE = 0xD00A
@@ -13,11 +15,13 @@ ADDR_CORRECTION = 0xD022
 ADDR_CALIBRATION_RESERVED_START = 0xD02E
 ADDR_CALIBRATION_RESERVED_END = 0xD04D
 
+# 协议数据宽度和位姿字段顺序。
 REGISTER_COUNT_WORD = 1
 REGISTER_COUNT_POSE = 12
 REGISTER_COUNT_CALIBRATION_RESERVED = 32
 AXIS_NAMES = ("x", "y", "z", "a", "b", "c")
 
+# 默认串口通信参数。
 DEFAULT_BAUDRATE = 115200
 DEFAULT_BYTESIZE = 8
 DEFAULT_PARITY = "N"

src/line_laser_modbus/models.py

@@ -107,8 +107,10 @@ def can_switch_mode(
     if current_mode is ModeCommand.EMERGENCY_STOP:
         return False
     if current_status is DeviceStatus.CALIBRATION_DONE:
+        # 标定完成后由控制器内部回待机，不直接进入运行模式。
         return False
     if current_status is DeviceStatus.TEACHING_DONE:
+        # 示教完成后可进入依赖标准轨迹的运行模式。
         return target_mode in {
             ModeCommand.ONLINE_TRACKING,
             ModeCommand.TRAJECTORY_REPLAY,