Add FFmpeg utilities configuration UI and automated downloading

Introduce a new UI for configuring FFmpeg, FFprobe, and FFplay paths with file selection and error handling. Add platform-specific logic for downloading and extracting FFmpeg binaries directly within the application, improving user experience.

internal/controller/convertor.go

@@ -1,8 +1,58 @@
 package controller
 
-import "git.kor-elf.net/kor-elf/gui-for-ffmpeg/internal/gui/view"
+import (
+	"git.kor-elf.net/kor-elf/gui-for-ffmpeg/internal/ffmpeg/download/service"
+	"git.kor-elf.net/kor-elf/gui-for-ffmpeg/internal/gui/view"
+)
 
 func (c *controller) convertor() {
 	content := view.Convertor()
 	c.window.SetContent(content)
 }
+
+func (c *controller) settingConvertor(isAllowCancellation bool) {
+	ffmpegPath := c.app.GetFFmpegService().GetFFmpegPath()
+	ffprobePath := c.app.GetFFmpegService().GetFFprobePath()
+	ffplayPath := c.app.GetFFmpegService().GetFFplayPath()
+
+	var cancel func()
+	cancel = nil
+	if isAllowCancellation {
+		cancel = func() {
+			c.convertor()
+		}
+	}
+
+	content := view.ConfiguringFFmpegUtilities(
+		c.window,
+		ffmpegPath,
+		ffprobePath,
+		ffplayPath,
+		c.saveSettingConvertor,
+		cancel,
+		service.DownloadFFmpeg(c.app, c.saveSettingConvertor),
+	)
+	c.window.SetContent(content)
+}
+
+func (c *controller) saveSettingConvertor(ffmpegPath string, ffprobePath string, ffplayPath string) error {
+	var err error
+
+	err = c.app.GetFFmpegService().ChangeFFmpeg(ffmpegPath)
+	if err != nil {
+		return err
+	}
+
+	c.app.GetFFmpegService().ChangeFFprobe(ffprobePath)
+	if err != nil {
+		return err
+	}
+
+	c.app.GetFFmpegService().ChangeFFplay(ffplayPath)
+	if err != nil {
+		return err
+	}
+
+	c.convertor()
+	return nil
+}