Refactor localization system and migrate to Fyne's built-in support

Replaced the `i18n` and `toml` dependencies with Fyne's built-in language system for localization management. Updated the `Localizer` implementation to handle translations using JSON files and embed functionality. Simplified language selection and persisted settings via Fyne's preferences API.

error/view.go

@@ -2,11 +2,9 @@ package error
 
 import (
 	"fyne.io/fyne/v2/container"
-	"fyne.io/fyne/v2/lang"
 	"fyne.io/fyne/v2/widget"
 	"git.kor-elf.net/kor-elf/gui-for-ffmpeg/kernel"
 	"git.kor-elf.net/kor-elf/gui-for-ffmpeg/localizer"
-	"github.com/nicksnyder/go-i18n/v2/i18n"
 )
 
 type ViewContract interface {
@@ -14,26 +12,17 @@ type ViewContract interface {
 }
 
 type View struct {
-	app           kernel.AppContract
-	isSetLanguage bool
+	app kernel.AppContract
 }
 
 func NewView(app kernel.AppContract) *View {
 	return &View{
-		app:           app,
-		isSetLanguage: true,
+		app: app,
 	}
 }
 
 func (v View) PanicError(err error) {
-	if v.isSetLanguage {
-		v.isSetLanguage = false
-		_ = v.app.GetLocalizerService().SetCurrentLanguageByCode(lang.SystemLocale().LanguageString())
-	}
-
-	messageHead := v.app.GetLocalizerService().GetMessage(&i18n.LocalizeConfig{
-		MessageID: "error",
-	})
+	messageHead := v.app.GetLocalizerService().GetMessage("error")
 
 	v.app.GetWindow().SetContent(container.NewBorder(
 		container.NewVBox(