Fix WidgetPool goroutine and ticker leak

- Add context cancellation to WidgetPool cleanup goroutine
- Properly stop ticker when context is canceled
- Add BackgroundContext() getter method to App for context access
- Pass application context to NewWidgetPool for lifecycle management

This fixes a resource leak where the cleanup goroutine would run
indefinitely without any way to stop it, preventing proper cleanup
on application shutdown.

backend/app.go

@@ -504,6 +504,12 @@ func (a *App) DeleteServerCacheDir(serverID uuid.UUID) error {
 	return os.RemoveAll(path)
 }
 
+// BackgroundContext returns the application's background context
+// which is canceled when the application shuts down.
+func (a *App) BackgroundContext() context.Context {
+	return a.bgrndCtx
+}
+
 func (a *App) Shutdown() {
 	if a.logFile != nil {
 		a.logFile.Close()

ui/browsing/router.go

@@ -26,7 +26,7 @@ func NewRouter(app *backend.App, controller *controller.Controller, nav Navigati
 		App:        app,
 		Controller: controller,
 		Nav:        nav,
-		widgetPool: util.NewWidgetPool(),
+		widgetPool: util.NewWidgetPool(app.BackgroundContext()),
 	}
 	return r
 }

ui/util/widgetpool.go

@@ -1,6 +1,7 @@
 package util
 
 import (
+	"context"
 	"sync"
 	"time"
 
@@ -33,6 +34,7 @@ const (
 type WidgetPool struct {
 	mut    sync.Mutex
 	pools  [][]pooledWidget
+	cancel context.CancelFunc
 }
 
 type pooledWidget struct {
@@ -40,15 +42,23 @@ type pooledWidget struct {
 	releasedAt int64 // unixMillis
 }
 
-func NewWidgetPool() *WidgetPool {
+func NewWidgetPool(ctx context.Context) *WidgetPool {
+	ctx, cancel := context.WithCancel(ctx)
 	p := &WidgetPool{
 		pools:  make([][]pooledWidget, numWidgetTypes),
+		cancel: cancel,
 	}
 	go func() {
 		t := time.NewTicker(2 * time.Minute)
-		for range t.C {
+		defer t.Stop()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-t.C:
 				p.cleanUpExpiredItems()
 			}
+		}
 	}()
 	return p
 }