fix: 修复书源导入、阅读外观和书签状态

- 修复书源文件选择、访问权限与导入预览流程，支持查看分组内的书源
- 修复背景图片、字体选择与主题切换，限制背景图片解码尺寸
- 根据已保存书签恢复当前位置状态，避免重复添加
- 补充模型、阅读器和文件选择回归测试及测试样本
- 更新应用版本为 0.1.10（build 16）

Fixes #1

scripts/fixtures/SourceImportFixture.swift

@@ -0,0 +1,33 @@
+import UIKit
+
+// Standalone simulator-only file provider; never bundled with Legado.
+@main
+@MainActor
+final class FixtureAppDelegate: UIResponder, UIApplicationDelegate {
+    var window: UIWindow?
+
+    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
+        let documents = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
+        let fixtures = [
+            ("JSON-Source.json", "https://file-import.test/json", "文件导入 JSON 测试"),
+            ("JSON-Uppercase.JSON", "https://file-import.test/uppercase", "文件导入大写扩展名测试"),
+            ("JSON-Text.txt", "https://file-import.test/text", "文件导入文本扩展名测试")
+        ]
+        for (name, url, title) in fixtures {
+            let source = [["bookSourceUrl": url, "bookSourceName": title]]
+            if let data = try? JSONSerialization.data(withJSONObject: source) {
+                try? data.write(to: documents.appendingPathComponent(name), options: .atomic)
+            }
+        }
+        let controller = UIViewController()
+        controller.view.backgroundColor = .systemBackground
+        let label = UILabel()
+        label.text = "书源导入测试文件已准备好"
+        label.frame = CGRect(x: 20, y: 100, width: 350, height: 80)
+        controller.view.addSubview(label)
+        window = UIWindow(frame: UIScreen.main.bounds)
+        window?.rootViewController = controller
+        window?.makeKeyAndVisible()
+        return true
+    }
+}