feat: native clipboard image sync (Linux, opt-in sync_images)

internal/clipboard/clipboard_linux.go

@@ -3,6 +3,7 @@
 package clipboard
 
 import (
+	"bytes"
 	"fmt"
 	"os"
 	"os/exec"
@@ -70,3 +71,37 @@ func (c *linuxClipboard) Write(text string) error {
 	}
 	return nil
 }
+
+// ReadImage returns the PNG image from the clipboard, if any.
+func (c *linuxClipboard) ReadImage() (string, []byte, error) {
+	var args []string
+	if c.pasteCmd == "wl-paste" {
+		args = []string{"--type", "image/png"}
+	} else {
+		args = []string{"-selection", "clipboard", "-t", "image/png", "-o"}
+	}
+
+	cmd := exec.Command(c.pasteCmd, args...)
+	out, err := cmd.Output()
+	if err != nil || len(out) == 0 {
+		return "", nil, ErrNoImage
+	}
+	return "image/png", out, nil
+}
+
+// WriteImage writes image bytes to the clipboard using the given MIME type.
+func (c *linuxClipboard) WriteImage(mime string, data []byte) error {
+	var args []string
+	if c.copyCmd == "wl-copy" {
+		args = []string{"--type", mime}
+	} else {
+		args = []string{"-selection", "clipboard", "-t", mime}
+	}
+
+	cmd := exec.Command(c.copyCmd, args...)
+	cmd.Stdin = bytes.NewReader(data)
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("clipboard write image (%s): %w", c.copyCmd, err)
+	}
+	return nil
+}