feat: add EskinDeviceFunc FFI bindings and update Python/README

- Add FFI wrappers for all EskinDeviceFunc trait methods:
  eskin_read_hdw_version, eskin_read_matrix_row/col,
  eskin_read_device_config1/2, eskin_write_device_config1/2,
  eskin_write_matrix_row/col
- Extract sdk_error_to_code() helper for SdkError -> SdkErrorCode conversion
- Update C header (include/eskin_ffi.h) with new function declarations
- Update Python FFI bindings (example/python/eskin_ffi.py) with new methods
- Update README with Python usage instructions and full FFI interface table

example/python/example.py

@@ -0,0 +1,51 @@
+from eskin_ffi import EskinDevice
+
+def main():
+    dev = EskinDevice()
+
+    # SDK 版本
+    ver = dev.version()
+    print(f"ESkin SDK version: {ver[0]}.{ver[1]}.{ver[2]}")
+
+    # 打开设备
+    dev.open("/dev/ttyUSB0")
+    print("Device opened")
+
+    try:
+        # 读取硬件版本
+        hdw_ver = dev.read_hdw_version()
+        print(f"Hardware version: {hdw_ver}")
+
+        # 读取矩阵尺寸
+        row = dev.read_matrix_row()
+        col = dev.read_matrix_col()
+        print(f"Matrix size: {row} x {col}")
+
+        # 读取设备配置
+        cfg1 = dev.read_device_config1()
+        # cfg2 = dev.read_device_config2()
+        print(f"Device config1: 0x{cfg1:02X}")
+        # print(f"Device config2: 0x{cfg2:02X}")
+
+        # 写入矩阵尺寸示例
+        # ret = dev.write_matrix_row(16)
+        # print(f"Write matrix row: returned {ret} bytes")
+        # ret = dev.write_matrix_col(16)
+        # print(f"Write matrix col: returned {ret} bytes")
+
+        # 写入设备配置示例
+        # ret = dev.write_device_config1(True)
+        # print(f"Write device config1: returned {ret} bytes")
+        # ret = dev.write_device_config2(False)
+        # print(f"Write device config2: returned {ret} bytes")
+
+        # 原始寄存器读写
+        data = dev.read_register(0x1C00, 168)
+        print(f"Serial number: {data.hex().upper()}")
+
+    finally:
+        dev.close()
+        print("Device closed")
+
+if __name__ == "__main__":
+    main()