Simplify threading solution and add Clear All button

Simplified the approach by removing complex callback logic and using a
simple 500ms timer-based update for the stats bar instead. This eliminates
threading errors completely while keeping the code straightforward.

Changes:
1. Removed queue change callback entirely
2. Added background timer that updates stats bar every 500ms
3. Removed initComplete flag (no longer needed)
4. Simplified setContent() to direct calls
5. Added onClearAll parameter to BuildQueueView()
6. Added ClearAll() method to Queue (removes all jobs)
7. Added Clear All button with DangerImportance styling in queue view
8. Clear Completed button now has LowImportance styling

This approach is much simpler: the UI just polls the queue state
periodically instead of trying to handle callbacks from goroutines.
No more threading errors, less code, easier to understand.

internal/queue/queue.go

@@ -378,6 +378,15 @@ func (q *Queue) Clear() {
 	q.notifyChange()
 }
 
+// ClearAll removes all jobs from the queue
+func (q *Queue) ClearAll() {
+	q.mu.Lock()
+	defer q.mu.Unlock()
+
+	q.jobs = make([]*Job, 0)
+	q.notifyChange()
+}
+
 // generateID generates a unique ID for a job
 func generateID() string {
 	return fmt.Sprintf("job-%d", time.Now().UnixNano())

internal/ui/queueview.go

@@ -21,6 +21,7 @@ func BuildQueueView(
 	onCancel func(string),
 	onRemove func(string),
 	onClear func(),
+	onClearAll func(),
 	titleColor, bgColor, textColor color.Color,
 ) fyne.CanvasObject {
 	// Header
@@ -29,12 +30,18 @@ func BuildQueueView(
 	title.TextSize = 24
 
 	backBtn := widget.NewButton("← Back", onBack)
+	backBtn.Importance = widget.LowImportance
+
 	clearBtn := widget.NewButton("Clear Completed", onClear)
+	clearBtn.Importance = widget.LowImportance
+
+	clearAllBtn := widget.NewButton("Clear All", onClearAll)
+	clearAllBtn.Importance = widget.DangerImportance
 
 	header := container.NewBorder(
 		nil, nil,
 		backBtn,
-		clearBtn,
+		container.NewHBox(clearBtn, clearAllBtn),
 		container.NewCenter(title),
 	)
 

main.go

@@ -151,31 +151,30 @@ func (c convertConfig) CoverLabel() string {
 }
 
 type appState struct {
-	window         fyne.Window
+	window        fyne.Window
-	active         string
+	active        string
-	initComplete   bool // True after initial UI setup completes
+	source        *videoSource
-	source         *videoSource
+	loadedVideos  []*videoSource // Multiple loaded videos for navigation
-	loadedVideos   []*videoSource // Multiple loaded videos for navigation
+	currentIndex  int            // Current video index in loadedVideos
-	currentIndex   int            // Current video index in loadedVideos
+	anim          *previewAnimator
-	anim           *previewAnimator
+	convert       convertConfig
-	convert        convertConfig
+	currentFrame  string
-	currentFrame   string
+	player        player.Controller
-	player         player.Controller
+	playerReady   bool
-	playerReady    bool
+	playerVolume  float64
-	playerVolume   float64
+	playerMuted   bool
-	playerMuted    bool
+	lastVolume    float64
-	lastVolume     float64
+	playerPaused  bool
-	playerPaused   bool
+	playerPos     float64
-	playerPos      float64
+	playerLast    time.Time
-	playerLast     time.Time
+	progressQuit  chan struct{}
-	progressQuit   chan struct{}
+	convertCancel context.CancelFunc
-	convertCancel  context.CancelFunc
+	playerSurf    *playerSurface
-	playerSurf     *playerSurface
+	convertBusy   bool
-	convertBusy    bool
+	convertStatus string
-	convertStatus  string
+	playSess      *playSession
-	playSess       *playSession
+	jobQueue      *queue.Queue
-	jobQueue       *queue.Queue
+	statsBar      *ui.ConversionStatsBar
-	statsBar       *ui.ConversionStatsBar
 }
 
 func (s *appState) stopPreview() {
@@ -425,6 +424,10 @@ func (s *appState) showQueue() {
 			s.jobQueue.Clear()
 			s.showQueue() // Refresh
 		},
+		func() { // onClearAll
+			s.jobQueue.ClearAll()
+			s.showQueue() // Refresh
+		},
 		utils.MustHex("#4CE870"), // titleColor
 		gridColor,                // bgColor
 		textColor,                // textColor
@@ -1082,39 +1085,27 @@ func runGUI() {
 	// Start queue processing (but paused by default)
 	state.jobQueue.Start()
 
-	// Set callback - queue changes are triggered by job processor goroutine
-	state.jobQueue.SetChangeCallback(func() {
-		// Skip updates during initialization
-		if !state.initComplete {
-			return
-		}
-
-		// Marshal UI updates to main thread
-		app := fyne.CurrentApp()
-		if app == nil || app.Driver() == nil {
-			return
-		}
-
-		app.Driver().DoFromGoroutine(func() {
-			// Update stats bar
-			state.updateStatsBar()
-
-			// Refresh UI when queue changes and we're on main menu
-			if state.active == "" {
-				state.showMainMenu()
-			}
-		}, false)
-	})
-
-	// Mark initialization as complete
-	state.initComplete = true
-
 	defer state.shutdown()
 	w.SetOnDropped(func(pos fyne.Position, items []fyne.URI) {
 		state.handleDrop(pos, items)
 	})
 	state.showMainMenu()
 	logging.Debug(logging.CatUI, "main menu rendered with %d modules", len(modulesList))
+
+	// Start stats bar update loop on a timer
+	go func() {
+		ticker := time.NewTicker(500 * time.Millisecond)
+		defer ticker.Stop()
+		for range ticker.C {
+			app := fyne.CurrentApp()
+			if app != nil && app.Driver() != nil {
+				app.Driver().DoFromGoroutine(func() {
+					state.updateStatsBar()
+				}, false)
+			}
+		}
+	}()
+
 	w.ShowAndRun()
 }