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
+    }
+}

scripts/prepare-source-import-fixture.sh

@@ -0,0 +1,45 @@
+#!/bin/sh
+set -eu
+
+if [ "$#" -ne 1 ]; then
+    printf 'Usage: sh scripts/prepare-source-import-fixture.sh <booted-simulator-UUID>\n' >&2
+    exit 2
+fi
+
+legado_fixture_device="$1"
+legado_fixture_repo="$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)"
+legado_fixture_build="$(mktemp -d "${TMPDIR:-/tmp}/legado-source-import.XXXXXX")"
+trap 'rm -rf "$legado_fixture_build"' EXIT HUP INT TERM
+legado_fixture_app="$legado_fixture_build/SourceImportFixtures.app"
+legado_fixture_sdk="$(xcrun --sdk iphonesimulator --show-sdk-path)"
+legado_fixture_arch="$(uname -m)"
+mkdir -p "$legado_fixture_app"
+
+cat > "$legado_fixture_app/Info.plist" <<'PLIST'
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0"><dict>
+    <key>CFBundleIdentifier</key><string>com.epiboly.legado.source-import-fixtures</string>
+    <key>CFBundleExecutable</key><string>SourceImportFixtures</string>
+    <key>CFBundleName</key><string>SourceImportFixtures</string>
+    <key>CFBundleDisplayName</key><string>书源导入测试</string>
+    <key>CFBundlePackageType</key><string>APPL</string>
+    <key>CFBundleVersion</key><string>1</string>
+    <key>CFBundleShortVersionString</key><string>1.0</string>
+    <key>MinimumOSVersion</key><string>15.0</string>
+    <key>LSRequiresIPhoneOS</key><true/>
+    <key>UIFileSharingEnabled</key><true/>
+    <key>LSSupportsOpeningDocumentsInPlace</key><true/>
+    <key>UILaunchScreen</key><dict/>
+    <key>UISupportedInterfaceOrientations</key><array><string>UIInterfaceOrientationPortrait</string></array>
+</dict></plist>
+PLIST
+
+xcrun --sdk iphonesimulator swiftc -parse-as-library -swift-version 6 \
+    -sdk "$legado_fixture_sdk" -target "$legado_fixture_arch-apple-ios15.0-simulator" \
+    -module-cache-path "$legado_fixture_repo/DerivedData/ModuleCache.noindex" \
+    "$legado_fixture_repo/scripts/fixtures/SourceImportFixture.swift" \
+    -o "$legado_fixture_app/SourceImportFixtures"
+xcrun simctl install "$legado_fixture_device" "$legado_fixture_app"
+xcrun simctl launch --terminate-running-process "$legado_fixture_device" com.epiboly.legado.source-import-fixtures
+printf 'JSON file import fixtures are ready in Files > On My iPhone > 书源导入测试.\n'