Bidirectional progress sync, reliable background history, MB-accurate download ring

- Bidirectional progress sync: server's `lastUpdate` now parsed correctly; pull
  timer (60s) + scenePhase hook reconcile against local state. Server-newer
  while paused/playing stashes a `pendingServerProgress` and surfaces a prompt
  on next Play; server-older triggers an immediate push.
- History: lockscreen/Control-Center skip & scrub now route through AppState
  via `onRemoteSkip`/`onRemoteSeek` callbacks (previously bypassed history).
  `AppState.skip(by:)` itself now records the pre-skip position.
- Chapter detection moved to the AVPlayer periodic time observer — fires
  reliably while the app is backgrounded or the device is locked, where the
  5s runloop Timer can be throttled.
- Always fetch item detail when online (even for downloaded items) so
  `item.chapters` is populated and history entries get chapter titles.
- DownloadManager: per-track byte-fraction progress, so single-track 1+GB
  audiobooks' ring grows smoothly instead of staying at 0% until done.
- PlayerBar: extracted ScrubberView into its own struct so per-second time
  updates no longer re-render the parent (fixes iOS history-popup flicker).
- App icon: re-embedded sRGB profile in marketing icon; bumped version 2.0
  to 2.1.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ABS Client/Audiobookshelf swift/Services/DownloadManager.swift

@@ -76,6 +76,11 @@ final class DownloadManager: @unchecked Sendable {
     /// Bytes received for the currently in-flight track per downloadKey.
     /// Reset between tracks; cleared when the download finishes/cancels.
     private(set) var inFlightBytes: [String: Int64] = [:]
+    /// Current track index (0-based) per active download. Set at the start of
+    /// each track iteration, cleared via defer when the download exits.
+    private var currentTrackIndex: [String: Int] = [:]
+    /// Total number of tracks per active download.
+    private var totalTrackCount: [String: Int] = [:]
 
     private var indexFile: URL { AppPaths.supportDirectory.appendingPathComponent("downloads-index.json") }
     private var activeTasks: [String: Task<Void, Never>] = [:]
@@ -118,6 +123,21 @@ final class DownloadManager: @unchecked Sendable {
         }
     }
 
+    /// Called from the URL session delegate with the fraction (0…1) of the
+    /// currently downloading track. Combines with the completed-track count to
+    /// drive a smooth overall progress ring, even for single-track downloads.
+    nonisolated func _reportTrackByteFraction(_ fraction: Double, for downloadKey: String) {
+        Task { @MainActor [self] in
+            guard let idx = self.currentTrackIndex[downloadKey],
+                  let total = self.totalTrackCount[downloadKey],
+                  total > 0 else { return }
+            let overall = (Double(idx) + max(0, min(1, fraction))) / Double(total)
+            // Clamp below 1.0 so `performDownload` is the only place that
+            // transitions to `.downloaded` after the final track is persisted.
+            self.states[downloadKey] = .downloading(progress: min(0.999, overall))
+        }
+    }
+
     private func fileSize(at url: URL) -> Int64 {
         guard let attrs = try? FileManager.default.attributesOfItem(atPath: url.path) else { return 0 }
         if let n = attrs[.size] as? NSNumber { return n.int64Value }
@@ -218,6 +238,8 @@ final class DownloadManager: @unchecked Sendable {
         defer {
             pendingItems.removeValue(forKey: downloadKey)
             inFlightBytes.removeValue(forKey: downloadKey)
+            currentTrackIndex.removeValue(forKey: downloadKey)
+            totalTrackCount.removeValue(forKey: downloadKey)
         }
         let itemDir = directoryURL(itemId: workItem.id, episodeId: workItem.episodeId)
         do {
@@ -229,6 +251,7 @@ final class DownloadManager: @unchecked Sendable {
 
         var tracks: [DownloadedTrack] = []
         let total = max(workItem.audioFiles.count, 1)
+        totalTrackCount[downloadKey] = total
 
         for (idx, file) in workItem.audioFiles.enumerated() {
             if Task.isCancelled {
@@ -238,6 +261,7 @@ final class DownloadManager: @unchecked Sendable {
             guard let url = client.audioFileURL(itemId: workItem.id, ino: file.ino) else { continue }
             var request = URLRequest(url: url)
             for (k, v) in client.bearerHeader { request.setValue(v, forHTTPHeaderField: k) }
+            currentTrackIndex[downloadKey] = idx
 
             let tempURL: URL
             do {
@@ -418,6 +442,10 @@ private final class DownloadProgressDelegate: NSObject, URLSessionDownloadDelega
         totalBytesExpectedToWrite: Int64
     ) {
         manager._updateInFlightBytes(totalBytesWritten, for: downloadKey)
+        if totalBytesExpectedToWrite > 0 {
+            let fraction = Double(totalBytesWritten) / Double(totalBytesExpectedToWrite)
+            manager._reportTrackByteFraction(fraction, for: downloadKey)
+        }
     }
 
     func urlSession(