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

app/thanks/page.tsx

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+import { Suspense } from "react";
+import { ThanksView } from "./thanks-view";
+import { Loader2 } from "lucide-react";
+
+export const metadata = {
+  title: "感谢下载 · Koring Launcher",
+};
+
+export default function ThanksPage() {
+  return (
+    <Suspense
+      fallback={
+        <div className="flex flex-col items-center justify-center min-h-[60vh] gap-4">
+          <Loader2 className="size-8 animate-spin text-muted-foreground" />
+          <p className="text-muted-foreground">正在准备下载...</p>
+        </div>
+      }
+    >
+      <ThanksView />
+    </Suspense>
+  );
+}

app/thanks/thanks-view.tsx

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+"use client";
+
+import { useEffect, useMemo, useState } from "react";
+import Link from "next/link";
+import { useSearchParams } from "next/navigation";
+import { Button } from "@/components/ui/button";
+import {
+  PartyPopper,
+  Download,
+  ShieldCheck,
+  Copy,
+  Check,
+  RotateCw,
+  Monitor,
+  Apple,
+  Terminal,
+  AlertCircle,
+  ArrowRight,
+  type LucideIcon,
+} from "lucide-react";
+import { cn } from "@/lib/utils";
+import {
+  DOWNLOAD_SOURCES,
+  DOWNLOAD_OS_META,
+  isAllowedDownloadUrl,
+  type DownloadOsKey,
+} from "@/lib/download-sources";
+
+const OS_ICON: Record<string, LucideIcon> = {
+  windows: Monitor,
+  macos: Apple,
+  linux: Terminal,
+};
+
+export function ThanksView() {
+  const searchParams = useSearchParams();
+  const [autoStarted, setAutoStarted] = useState(false);
+  const [copied, setCopied] = useState(false);
+
+  const url = searchParams.get("url");
+  const osParam = searchParams.get("os") || "";
+  const sha512 = searchParams.get("sha512") || "";
+  const sourceKey = searchParams.get("source") || "";
+  const name = searchParams.get("name") || "";
+  const version = searchParams.get("version") || "";
+
+  const os = (
+    osParam === "windows" || osParam === "macos" || osParam === "linux"
+      ? osParam
+      : "windows"
+  ) as DownloadOsKey;
+  const osMeta = DOWNLOAD_OS_META[os];
+  const OsIcon = OS_ICON[os];
+
+  const allowed = isAllowedDownloadUrl(url);
+  const sourceLabel = useMemo(() => {
+    const s = DOWNLOAD_SOURCES.find((d) => d.key === sourceKey);
+    if (s) return s.label;
+    return sourceKey === "legacy" ? "官方缓存源" : sourceKey || "默认源";
+  }, [sourceKey]);
+
+  /** 触发浏览器下载（隐藏 a 标签，同页不离开） */
+  const triggerDownload = () => {
+    if (!allowed || !url) return;
+    const a = document.createElement("a");
+    a.href = url;
+    a.rel = "noopener noreferrer";
+    a.style.display = "none";
+    document.body.appendChild(a);
+    a.click();
+    a.remove();
+  };
+
+  // 自动开始下载
+  useEffect(() => {
+    if (!allowed || !url || autoStarted) return;
+    setAutoStarted(true);
+    const timer = setTimeout(triggerDownload, 800);
+    return () => clearTimeout(timer);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [url, allowed]);
+
+  const copySha = async () => {
+    if (!sha512) return;
+    try {
+      await navigator.clipboard.writeText(sha512);
+      setCopied(true);
+      setTimeout(() => setCopied(false), 1500);
+    } catch {
+      // 忽略剪贴板不可用
+    }
+  };
+
+  return (
+    <div className="flex flex-col items-center justify-center min-h-[70vh] w-full gap-8 px-4">
+      {/* 主卡片 */}
+      <div className="w-full max-w-xl rounded-3xl border border-border/50 bg-background/60 backdrop-blur-xl p-8 md:p-10 text-center">
+        {allowed ? (
+          <>
+            <div className="mx-auto flex size-16 items-center justify-center rounded-full bg-emerald-500/10">
+              <PartyPopper className="size-8 text-emerald-500" />
+            </div>
+            <h1 className="mt-5 text-2xl md:text-3xl font-bold tracking-tight">
+              感谢下载 Koring Launcher
+            </h1>
+            <p className="mt-2 text-sm text-muted-foreground leading-relaxed">
+              {autoStarted
+                ? "下载已自动开始，如果未弹出请点击下方按钮"
+                : "下载即将自动开始…"}
+            </p>
+
+            {/* 下载内容摘要 */}
+            <div className="mt-6 flex flex-col gap-3 text-left">
+              <div className="flex items-center gap-3 rounded-xl border border-border/50 p-3">
+                <div className="flex size-10 shrink-0 items-center justify-center rounded-lg bg-primary/10">
+                  <OsIcon className="size-5 text-primary" />
+                </div>
+                <div className="min-w-0">
+                  <p className="text-xs text-muted-foreground">
+                    下载类型 · {osMeta.hint}
+                  </p>
+                  <p className="truncate font-medium text-sm">
+                    {name || `${osMeta.label} 安装包`}
+                    {version ? `（v${version}）` : ""}
+                  </p>
+                </div>
+              </div>
+
+              <div className="flex items-center gap-3 rounded-xl border border-border/50 p-3">
+                <div className="flex size-10 shrink-0 items-center justify-center rounded-lg bg-primary/10">
+                  <Download className="size-5 text-primary" />
+                </div>
+                <div className="min-w-0">
+                  <p className="text-xs text-muted-foreground">加速类型</p>
+                  <p className="truncate font-medium text-sm">{sourceLabel}</p>
+                </div>
+              </div>
+
+              <button
+                type="button"
+                onClick={copySha}
+                disabled={!sha512}
+                title={sha512 ? "点击复制 SHA512" : undefined}
+                className="flex items-center gap-3 rounded-xl border border-border/50 p-3 text-left transition-colors hover:border-primary/50"
+              >
+                <div className="flex size-10 shrink-0 items-center justify-center rounded-lg bg-primary/10">
+                  <ShieldCheck className="size-5 text-primary" />
+                </div>
+                <div className="min-w-0 flex-1">
+                  <p className="text-xs text-muted-foreground">
+                    SHA512 校验值
+                    {sha512 && (copied ? "（已复制）" : "（点击复制）")}
+                  </p>
+                  <p className="truncate font-mono text-xs text-muted-foreground">
+                    {sha512 || "未提供"}
+                  </p>
+                </div>
+              </button>
+            </div>
+
+            {/* 操作 */}
+            <div className="mt-7 flex flex-col sm:flex-row items-center justify-center gap-3">
+              <Button size="lg" onClick={triggerDownload}>
+                <RotateCw className="size-4" />
+                重新下载
+              </Button>
+              <Button variant="outline" size="lg" asChild>
+                <Link href="/download">
+                  返回下载中心
+                  <ArrowRight className="size-4" />
+                </Link>
+              </Button>
+            </div>
+          </>
+        ) : (
+          <>
+            <div className="mx-auto flex size-16 items-center justify-center rounded-full bg-destructive/10">
+              <AlertCircle className="size-8 text-destructive" />
+            </div>
+            <h1 className="mt-5 text-2xl font-bold tracking-tight">
+              下载链接无效
+            </h1>
+            <p className="mt-2 text-sm text-muted-foreground leading-relaxed">
+              下载地址不在允许范围内，未自动开始下载。
+            </p>
+            <div className="mt-7">
+              <Button variant="outline" size="lg" asChild>
+                <Link href="/download">
+                  返回下载中心
+                  <ArrowRight className="size-4" />
+                </Link>
+              </Button>
+            </div>
+          </>
+        )}
+      </div>
+
+      {/* 底部提示 */}
+      {allowed && (
+        <p className={cn("max-w-xl text-center text-xs text-muted-foreground")}>
+          如浏览器拦截下载，请点击上方"重新下载"；安装时建议校验文件 SHA512 完整性。
+        </p>
+      )}
+    </div>
+  );
+}