feat: add remote screenshot and shell execution capabilities

- Add screenshot capture API with quality control
- Add remote shell command execution with timeout
- Implement client-side handlers for screenshot and shell requests
- Add Web UI components for screenshot viewing and shell terminal
- Support auto-refresh for screenshot monitoring
- Add shell command history navigation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkg/utils/screenshot.go

@@ -0,0 +1,98 @@
+package utils
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"image/jpeg"
+
+	"github.com/kbinani/screenshot"
+)
+
+// CaptureScreenshot 捕获主屏幕截图
+// quality: JPEG 质量 (1-100), 0 使用默认值 (75)
+// 返回: JPEG 图片数据, 宽度, 高度, 错误
+func CaptureScreenshot(quality int) ([]byte, int, int, error) {
+	// 默认质量
+	if quality <= 0 || quality > 100 {
+		quality = 75
+	}
+
+	// 获取活动显示器数量
+	n := screenshot.NumActiveDisplays()
+	if n == 0 {
+		return nil, 0, 0, fmt.Errorf("no active display found")
+	}
+
+	// 获取主显示器边界
+	bounds := screenshot.GetDisplayBounds(0)
+	if bounds.Empty() {
+		return nil, 0, 0, fmt.Errorf("failed to get display bounds")
+	}
+
+	// 捕获屏幕
+	img, err := screenshot.CaptureRect(bounds)
+	if err != nil {
+		return nil, 0, 0, fmt.Errorf("capture screen: %w", err)
+	}
+
+	// 编码为 JPEG
+	var buf bytes.Buffer
+	opts := &jpeg.Options{Quality: quality}
+	if err := jpeg.Encode(&buf, img, opts); err != nil {
+		return nil, 0, 0, fmt.Errorf("encode jpeg: %w", err)
+	}
+
+	return buf.Bytes(), bounds.Dx(), bounds.Dy(), nil
+}
+
+// CaptureAllScreens 捕获所有屏幕并拼接
+// quality: JPEG 质量 (1-100), 0 使用默认值 (75)
+// 返回: JPEG 图片数据, 宽度, 高度, 错误
+func CaptureAllScreens(quality int) ([]byte, int, int, error) {
+	// 默认质量
+	if quality <= 0 || quality > 100 {
+		quality = 75
+	}
+
+	// 获取活动显示器数量
+	n := screenshot.NumActiveDisplays()
+	if n == 0 {
+		return nil, 0, 0, fmt.Errorf("no active display found")
+	}
+
+	// 计算所有屏幕的总边界
+	var totalBounds image.Rectangle
+	for i := 0; i < n; i++ {
+		bounds := screenshot.GetDisplayBounds(i)
+		totalBounds = totalBounds.Union(bounds)
+	}
+
+	// 创建总画布
+	totalImg := image.NewRGBA(totalBounds)
+
+	// 捕获每个屏幕并绘制到总画布
+	for i := 0; i < n; i++ {
+		bounds := screenshot.GetDisplayBounds(i)
+		img, err := screenshot.CaptureRect(bounds)
+		if err != nil {
+			continue // 跳过失败的屏幕
+		}
+
+		// 绘制到总画布
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			for x := bounds.Min.X; x < bounds.Max.X; x++ {
+				totalImg.Set(x, y, img.At(x-bounds.Min.X, y-bounds.Min.Y))
+			}
+		}
+	}
+
+	// 编码为 JPEG
+	var buf bytes.Buffer
+	opts := &jpeg.Options{Quality: quality}
+	if err := jpeg.Encode(&buf, totalImg, opts); err != nil {
+		return nil, 0, 0, fmt.Errorf("encode jpeg: %w", err)
+	}
+
+	return buf.Bytes(), totalBounds.Dx(), totalBounds.Dy(), nil
+}