Add layout system and file selection logic

Introduce a new layout system for managing main window content and tabs. Integrate file selection and drag-and-drop functionality for adding files to the conversion list, with automatic tab switching to "Added Files". Refactor existing components to support these features.

internal/application/convertor/queue.go

@@ -1,9 +1,12 @@
 package convertor
 
-import "errors"
+import (
+	"errors"
+	"git.kor-elf.net/kor-elf/gui-for-ffmpeg/internal/ffmpeg"
+)
 
 type Queue struct {
-	Setting *ConvertSetting
+	Setting *ffmpeg.ConvertSetting
 	Status  StatusContract
 	Error   error
 }
@@ -46,7 +49,7 @@ type QueueListenerContract interface {
 type QueueListContract interface {
 	AddListener(queueListener QueueListenerContract)
 	GetItems() map[int]*Queue
-	Add(setting *ConvertSetting)
+	Add(setting *ffmpeg.ConvertSetting)
 	EventChangeQueue(key int, queue *Queue)
 	Remove(key int)
 	GetItem(key int) (*Queue, error)
@@ -72,7 +75,7 @@ func (l *queueList) GetItems() map[int]*Queue {
 	return l.items
 }
 
-func (l *queueList) Add(setting *ConvertSetting) {
+func (l *queueList) Add(setting *ffmpeg.ConvertSetting) {
 	queue := Queue{
 		Setting: setting,
 		Status:  StatusType(Waiting),