fix: 自定义颜色色块与预设色块保持一致，拾色浮窗改为锚点定位并放行面板内点击

- 自定义颜色入口改为与预设色块完全一致的呈现：当前颜色不在预设中时，
  方格直接填充该自定义颜色（并自动选择浅色/深色加号图标以保证可读性），
  外框尺寸与选中样式与预设色块完全相同。
- 拾色浮窗改为以触发控件矩形为锚点定位：优先紧贴其下方展开，空间不足时改到上方，
  修复此前浮窗遮挡「加号」方格的问题。
- 拾色浮窗展开时点击面板内的其它控件（预设色、线宽、样式、透明度等）不再被吞掉，
  改为「先收起浮窗、再放行该次点击」，一次点击即可切换预设色；
  点击面板外或绘图区仍只收起浮窗。

Utilities/Src/ColorPickerPopup.cpp

@@ -111,27 +111,30 @@ namespace jdi
 		return true;
 	}
 
-	void ColorPickerPopup::BuildLayout(const gd::RectF& bounds, int x, int y)
+	void ColorPickerPopup::BuildLayout(const gd::RectF& bounds, const gd::RectF& anchor)
 	{
 		const float width = kPanelWidth * m_scale;
 		const float height = (kPadV * 2.0f + kTitleHeight + kTitleGap + kRowHeight * 3.0f + kRowGap * 2.0f +
 		                      kPreviewGap + kPreviewHeight) *
 		                     m_scale;
 
-		float left = static_cast<float>(x);
-		float top = static_cast<float>(y);
+		const float gap = 4.0f * m_scale;
 
-		// 优先向右下展开；越界时翻转，最后做边界收敛。
-		if (left + width > bounds.X + bounds.Width)
-		{
-			left = static_cast<float>(x) - width;
-		}
+		// 纵向：优先紧贴触发控件下方展开；空间不足时改到其上方，避免遮挡触发控件本身。
+		float top = anchor.Y + anchor.Height + gap;
 		if (top + height > bounds.Y + bounds.Height)
 		{
-			top = static_cast<float>(y) - height;
+			top = anchor.Y - height - gap;
+		}
+		top = std::max(bounds.Y + 2.0f, std::min(top, bounds.Y + bounds.Height - height - 2.0f));
+
+		// 横向：与触发控件左对齐，越界时再收敛。
+		float left = anchor.X;
+		if (left + width > bounds.X + bounds.Width)
+		{
+			left = anchor.X + anchor.Width - width;
 		}
 		left = std::max(bounds.X + 2.0f, std::min(left, bounds.X + bounds.Width - width - 2.0f));
-		top = std::max(bounds.Y + 2.0f, std::min(top, bounds.Y + bounds.Height - height - 2.0f));
 
 		m_rect = gd::RectF(left, top, width, height);
 
@@ -160,7 +163,7 @@ namespace jdi
 		                      96.0f * m_scale, 20.0f * m_scale);
 	}
 
-	void ColorPickerPopup::Open(const gd::RectF& bounds, int x, int y, std::uint32_t color)
+	void ColorPickerPopup::Open(const gd::RectF& bounds, const gd::RectF& anchor, std::uint32_t color)
 	{
 		m_channels[0] = static_cast<double>((color >> 16) & 0xFFu) / 255.0;
 		m_channels[1] = static_cast<double>((color >> 8) & 0xFFu) / 255.0;
@@ -171,7 +174,7 @@ namespace jdi
 		m_draggingSlider = -1;
 		m_hoverSlider = -1;
 
-		BuildLayout(bounds, x, y);
+		BuildLayout(bounds, anchor);
 	}
 
 	void ColorPickerPopup::Close()