feat(download): 新增感谢下载页面并重构下载流程

- 新增专用的感谢下载页面，支持自动触发下载、SHA512校验值复制与手动重试下载
- 新增下载链接白名单校验机制，避免不安全的任意地址跳转与下载
- 重构官方下载页与测试版申请页面的下载逻辑，统一通过感谢页面完成全流程下载

lib/download-sources.ts

@@ -19,3 +19,53 @@ export const DATA_MIRRORS = [
   "https://gh-proxy.com",
   "https://ghfast.top",
 ] as const;
+
+/** 允许跳转到感谢页并自动下载的地址前缀（官方直链 + 镜像 + 自建 CDN） */
+const ALLOWED_DOWNLOAD_PREFIXES = [
+  "https://github.com/dream-pep/koring-launcher/releases/download/",
+  "https://gh.ddlc.top/https://github.com/dream-pep/koring-launcher/releases/download/",
+  "https://gh-proxy.com/https://github.com/dream-pep/koring-launcher/releases/download/",
+  "https://ghfast.top/https://github.com/dream-pep/koring-launcher/releases/download/",
+  "https://koring-file-api.lenjing.games/",
+  "https://koring-launcher-file-api.lenjing.cloud/",
+];
+
+/** 校验下载链接是否在白名单内（防止任意地址跳转/自动下载） */
+export function isAllowedDownloadUrl(
+  url: string | null | undefined
+): url is string {
+  return (
+    typeof url === "string" &&
+    ALLOWED_DOWNLOAD_PREFIXES.some((p) => url.startsWith(p))
+  );
+}
+
+export type DownloadOsKey = "windows" | "macos" | "linux";
+
+export const DOWNLOAD_OS_META: Record<
+  DownloadOsKey,
+  { label: string; hint: string }
+> = {
+  windows: { label: "Windows", hint: "Windows 安装包（exe）" },
+  macos: { label: "macOS", hint: "macOS 安装包" },
+  linux: { label: "Linux", hint: "Linux 安装包" },
+};
+
+/** 构造感谢下载页跳转地址（附带 下载链接 / 平台 / SHA512 / 加速类型） */
+export function buildDownloadThanksUrl(opts: {
+  url: string;
+  os: DownloadOsKey;
+  source: string;
+  sha512?: string;
+  name?: string;
+  version?: string;
+}) {
+  const p = new URLSearchParams();
+  p.set("url", opts.url);
+  p.set("os", opts.os);
+  p.set("source", opts.source);
+  if (opts.sha512) p.set("sha512", opts.sha512);
+  if (opts.name) p.set("name", opts.name);
+  if (opts.version) p.set("version", opts.version);
+  return `/thanks?${p.toString()}`;
+}