chore: trim redundant comments

ios/Runner/AppDelegate.swift

@@ -21,11 +21,8 @@ import Gobackend  // Import Go framework
     /// Currently accessed security-scoped URL for library folder
     private var activeSecurityScopedURL: URL?
 
-    /// Whether a download queue is currently active. When true, the app begins a
-    /// fresh background task each time it enters the background so an in-flight
-    /// download keeps running for the limited window iOS allows. iOS has no
-    /// foreground-service equivalent, so this is best-effort. Only touched on the
-    /// main thread.
+    /// Whether a download queue is active; while true a background task is
+    /// started on each background entry to extend execution time. Main-thread only.
     private var downloadsActive = false
     private var downloadBackgroundTask: UIBackgroundTaskIdentifier = .invalid
     
@@ -241,17 +238,12 @@ import Gobackend  // Import Go framework
     }
     
     private func handleMethodCall(call: FlutterMethodCall, result: @escaping FlutterResult) {
-        // Background-task management must run on the main thread and does not
-        // touch the Go backend, so handle it directly without dispatching.
         switch call.method {
         case "beginBackgroundDownloadTask":
-            // Queue started: remember it so we extend background time whenever
-            // the app is backgrounded while downloads run.
             downloadsActive = true
             result(nil)
             return
         case "endBackgroundDownloadTask":
-            // Queue finished/paused: stop extending background time.
             downloadsActive = false
             endBackgroundDownloadTask()
             result(nil)
@@ -283,14 +275,9 @@ import Gobackend  // Import Go framework
 
     override func applicationWillEnterForeground(_ application: UIApplication) {
         super.applicationWillEnterForeground(application)
-        // No background-time countdown while in the foreground.
         endBackgroundDownloadTask()
     }
 
-    /// Begins a background task (if one is not already active) so an in-flight
-    /// download keeps running for the limited window iOS allows after the app is
-    /// backgrounded. The expiration handler ends the task to avoid the app being
-    /// force-terminated by the watchdog. Must run on the main thread.
     private func beginBackgroundDownloadTask() {
         if downloadBackgroundTask != .invalid { return }
         downloadBackgroundTask = UIApplication.shared.beginBackgroundTask(