feat: background tasks panel (Phase 7)

Sources/Features/Conversation/ConversationView.swift

@@ -174,6 +174,23 @@ struct ConversationView: View {
 
     @ToolbarContentBuilder
     private var toolbarContent: some ToolbarContent {
+        ToolbarItem(placement: .topBarTrailing) {
+            NavigationLink {
+                TaskPanelView(taskStore: session.taskStore)
+            } label: {
+                Image(systemName: "tray.full")
+                    .overlay(alignment: .topTrailing) {
+                        if session.taskStore.activeCount > 0 {
+                            Text("\(session.taskStore.activeCount)")
+                                .font(.caption2.weight(.bold))
+                                .foregroundStyle(.white)
+                                .padding(3)
+                                .background(Color.red, in: Circle())
+                                .offset(x: 6, y: -6)
+                        }
+                    }
+            }
+        }
         ToolbarItem(placement: .topBarTrailing) {
             NavigationLink {
                 MediaPanelView(playerController: session.mediaController, settings: settings)