Add chapters, history, bookmarks, live download progress, and i18n

- Chapter navigation with auto-scroll to current chapter and end-of-chapter sleep timer
- Opt-in listening history (local-only) with XML export and per-item quick menu
- Bookmarks with server sync via Audiobookshelf API
- Live MB counter during downloads via URLSessionDownloadTask delegate
- In-progress downloads shown in "Heruntergeladen" with dimmed cover + ring overlay
- Cover image cache (50 MB memory / 500 MB disk URLCache)
- German/English localization (de.lproj, en.lproj)
- Loading spinner now triggers immediately on view switch instead of waiting for the network

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ABS Client/Audiobookshelf swift/Services/HistoryManager.swift

@@ -0,0 +1,98 @@
+import Foundation
+import Observation
+
+struct HistoryEntry: Codable, Identifiable {
+    let id: UUID
+    let timestamp: Date
+    let itemId: String
+    let episodeId: String?
+    let itemTitle: String
+    let itemAuthor: String
+    let chapterTitle: String?
+    let position: Double
+}
+
+@Observable
+@MainActor
+final class HistoryManager {
+    private(set) var entries: [HistoryEntry] = []
+
+    private static let maxEntries = 200
+    private var saveFile: URL {
+        AppPaths.supportDirectory.appendingPathComponent("history.json")
+    }
+
+    init() { load() }
+
+    func record(item: LibraryItem, position: Double, chapters: [Chapter]) {
+        guard position >= 0 else { return }
+        if let last = entries.first,
+           last.itemId == item.id,
+           last.episodeId == item.episodeId,
+           abs(last.position - position) < 15 { return }
+        let chapter = chapters.last { $0.start <= position }
+        let entry = HistoryEntry(
+            id: UUID(),
+            timestamp: Date(),
+            itemId: item.id,
+            episodeId: item.episodeId,
+            itemTitle: item.title,
+            itemAuthor: item.author,
+            chapterTitle: chapter?.title,
+            position: position
+        )
+        entries.insert(entry, at: 0)
+        if entries.count > Self.maxEntries { entries.removeLast() }
+        save()
+    }
+
+    func clear() {
+        entries.removeAll()
+        save()
+    }
+
+    func exportXML() -> URL? {
+        let formatter = ISO8601DateFormatter()
+        var xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+        xml += "<history exported=\"\(formatter.string(from: Date()))\">\n"
+        for entry in entries {
+            xml += "  <entry>\n"
+            xml += "    <timestamp>\(formatter.string(from: entry.timestamp))</timestamp>\n"
+            xml += "    <itemTitle>\(xmlEscape(entry.itemTitle))</itemTitle>\n"
+            xml += "    <itemAuthor>\(xmlEscape(entry.itemAuthor))</itemAuthor>\n"
+            if let chapter = entry.chapterTitle {
+                xml += "    <chapter>\(xmlEscape(chapter))</chapter>\n"
+            }
+            if let epId = entry.episodeId {
+                xml += "    <episodeId>\(xmlEscape(epId))</episodeId>\n"
+            }
+            xml += "    <position>\(entry.position)</position>\n"
+            xml += "  </entry>\n"
+        }
+        xml += "</history>\n"
+
+        let tmpURL = FileManager.default.temporaryDirectory
+            .appendingPathComponent("hoerverlauf.xml")
+        try? xml.write(to: tmpURL, atomically: true, encoding: .utf8)
+        return tmpURL
+    }
+
+    private func xmlEscape(_ s: String) -> String {
+        s.replacingOccurrences(of: "&", with: "&amp;")
+         .replacingOccurrences(of: "<", with: "&lt;")
+         .replacingOccurrences(of: ">", with: "&gt;")
+    }
+
+    private func save() {
+        try? FileManager.default.createDirectory(
+            at: AppPaths.supportDirectory, withIntermediateDirectories: true)
+        if let data = try? JSONEncoder().encode(entries) {
+            try? data.write(to: saveFile)
+        }
+    }
+
+    private func load() {
+        guard let data = try? Data(contentsOf: saveFile) else { return }
+        entries = (try? JSONDecoder().decode([HistoryEntry].self, from: data)) ?? []
+    }
+}