feat(fx): 添加像素排序 (Pixel Sort) 滤镜

- 新增 '像素排序' 滤镜，实现类似 Photoshop Pixel Sort 效果
- 支持水平/垂直方向排序
- 支持多种排序依据：亮度、色相、红/绿/蓝通道
- 支持自动阈值计算（使用图像亮度中位数）
- 支持自定义遮罩阈值
- 支持反向排序
- 支持块大小参数
- 添加相关单元测试

tests/test_fx_process.py

@@ -86,3 +86,67 @@ def test_prase_input_args_parses_resize_second_argument_as_float():
     assert len(filters) == 1
     assert filters[0].name == "缩放"
     assert filters[0].args == [2.0, 3.0]
+
+
+def test_apply_pixel_sort_keeps_image_mode_and_size():
+    """测试 Pixel Sort 保持图像的 mode 和 size"""
+    image = Image.new("RGBA", (10, 10), (255, 0, 0, 128))
+
+    result = ImageFilterImplement.apply_pixel_sort(image)
+
+    assert result.size == image.size
+    assert result.mode == "RGBA"
+
+
+def test_apply_pixel_sort_horizontal():
+    """测试水平方向的 Pixel Sort"""
+    # 创建一个简单的渐变图像
+    image = Image.new("RGB", (5, 3))
+    # 第一行：红到蓝渐变
+    image.putpixel((0, 0), (255, 0, 0))
+    image.putpixel((1, 0), (200, 0, 0))
+    image.putpixel((2, 0), (100, 0, 0))
+    image.putpixel((3, 0), (50, 0, 0))
+    image.putpixel((4, 0), (0, 0, 255))
+    # 填充其他行
+    for y in range(1, 3):
+        for x in range(5):
+            image.putpixel((x, y), (128, 128, 128))
+
+    result = ImageFilterImplement.apply_pixel_sort(
+        image, direction="horizontal", auto_threshold=False, mask_threshold=10
+    )
+
+    assert result.size == image.size
+    assert result.mode == "RGBA"
+
+
+def test_apply_pixel_sort_vertical():
+    """测试垂直方向的 Pixel Sort"""
+    image = Image.new("RGB", (3, 5))
+    # 第一列：绿到红渐变
+    image.putpixel((0, 0), (0, 255, 0))
+    image.putpixel((0, 1), (0, 200, 0))
+    image.putpixel((0, 2), (0, 100, 0))
+    image.putpixel((0, 3), (0, 50, 0))
+    image.putpixel((0, 4), (255, 0, 0))
+    # 填充其他列
+    for y in range(5):
+        for x in range(1, 3):
+            image.putpixel((x, y), (128, 128, 128))
+
+    result = ImageFilterImplement.apply_pixel_sort(
+        image, direction="vertical", auto_threshold=False, mask_threshold=10
+    )
+
+    assert result.size == image.size
+    assert result.mode == "RGBA"
+
+
+def test_prase_input_args_parses_pixel_sort_arguments():
+    """测试解析 Pixel Sort 参数"""
+    filters = prase_input_args("像素排序 horizontal 0 false brightness 128 false 1")
+
+    assert len(filters) == 1
+    assert filters[0].name == "像素排序"
+    assert filters[0].args == ["horizontal", 0.0, False, "brightness", 128.0, False, 1]