移动端下载器改版：重构为底部三标签的信息架构

- 以 TabBar + 三个视图（任务/搜索/设置）替换原有 DashBoard/Side/HentaiSearch 单页结构
- 拆分 TaskView / TaskRow / TaskDetailSheet / SearchView / SettingsView / AuthScreen
- 统一 theme.css 视觉规范，补 AppIcon 与缩略图工具 thumbnail.js 及其单测
- 提交弹层默认选中最高可用分辨率，缩略图加载失败走占位
- E站搜索结果与远端抽屉补回「在线看」入口

src/utils/thumbnail.js

@@ -0,0 +1,27 @@
+const BaseUrl = "https://downloader.lionwebsite.xyz/";
+
+// Remote galleries carry a raw thumbnail path; it only resolves through the
+// backend proxy once the active auth code is attached.
+export function ehThumbnailUrl(path, AuthCode) {
+  if (!path) return "";
+  return BaseUrl + "GalleryManage/ehThumbnail?" + new URLSearchParams({path, AuthCode}).toString();
+}
+
+const UNIT_SCALE = {b: 1, k: 1024, m: 1024 ** 2, g: 1024 ** 3, t: 1024 ** 4};
+
+function sizeInBytes(text) {
+  const match = String(text).match(/([\d.]+)\s*([kmgt]?)(?:i?b)/i);
+  if (!match) return 0;
+  const scale = UNIT_SCALE[match[2].toLowerCase()] ?? 1;
+  return Number(match[1]) * scale;
+}
+
+// Prefer the original file; otherwise take whichever entry reports the most bytes.
+export function pickDefaultResolution(availableResolution) {
+  const entries = Object.entries(availableResolution || {});
+  if (entries.length === 0) return "";
+  const original = entries.find(([resolution]) => /original/i.test(resolution));
+  if (original) return original[0];
+  return entries.reduce((best, current) =>
+    sizeInBytes(current[1]) > sizeInBytes(best[1]) ? current : best)[0];
+}