docs: rename contact page references to offline page in changelog

refactor(frontend): rename contact page to offline page and update routes/components

feat(frontend): add preset templates suite for offline contact page

frontend/lib/openflare/offline-page-templates/minimalist.ts

@@ -0,0 +1,128 @@
+/** 内置离线页模板：minimalist（默认） */
+const html = `
+<!DOCTYPE html>
+<html lang="zh-CN">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>离线页 | OpenFlare</title>
+  <style>
+    * { box-sizing: border-box; margin: 0; padding: 0; }
+    body {
+      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
+      background-color: #ffffff;
+      color: #333333;
+      min-height: 100vh;
+      display: flex;
+      flex-direction: column;
+      justify-content: center;
+      align-items: center;
+      text-align: center;
+      padding: 48px 24px;
+    }
+    .container {
+      max-width: 560px;
+      width: 100%;
+      display: flex;
+      flex-direction: column;
+      align-items: center;
+      gap: 24px;
+    }
+    .badge {
+      display: inline-flex;
+      align-items: center;
+      padding: 4px 12px;
+      border-radius: 9999px;
+      background-color: #f3f4f6;
+      color: #4b5563;
+      font-size: 12px;
+      font-weight: 500;
+      letter-spacing: 0.05em;
+    }
+    .title {
+      font-size: 32px;
+      font-weight: 700;
+      color: #111827;
+      line-height: 1.25;
+    }
+    .description {
+      font-size: 15px;
+      line-height: 1.6;
+      color: #6b7280;
+      max-width: 480px;
+    }
+    .contact-card {
+      width: 100%;
+      background: #f9fafb;
+      border: 1px solid #e5e7eb;
+      border-radius: 12px;
+      padding: 24px;
+      display: flex;
+      flex-direction: column;
+      gap: 16px;
+      text-align: left;
+    }
+    .contact-item {
+      display: flex;
+      align-items: center;
+      gap: 12px;
+      font-size: 14px;
+      color: #374151;
+    }
+    .contact-item svg {
+      width: 18px;
+      height: 18px;
+      color: #6b7280;
+      flex-shrink: 0;
+    }
+    .contact-item a {
+      color: #2563eb;
+      text-decoration: none;
+    }
+    .contact-item a:hover {
+      text-decoration: underline;
+    }
+    .footer {
+      margin-top: 32px;
+      display: flex;
+      align-items: center;
+      gap: 8px;
+      color: #9ca3af;
+      font-size: 13px;
+    }
+    .brand-icon {
+      width: 20px;
+      height: 20px;
+      fill: currentColor;
+    }
+  </style>
+</head>
+<body>
+<div class="container">
+  <div class="badge">OFFLINE CONTACT</div>
+  <h1 class="title">站点暂不可用，联系站长</h1>
+  <p class="description">
+    当前无法连接至源站。页面已开启 Service Worker 离线保护，您可以通过以下方式与站长取得联系。
+  </p>
+  <div class="contact-card">
+    <div class="contact-item">
+      <svg fill="none" stroke="currentColor" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M3 8l7.89 5.26a2 2 0 002.22 0L21 8M5 19h14a2 2 0 002-2V7a2 2 0 00-2-2H5a2 2 0 00-2 2v10a2 2 0 002 2z"></path></svg>
+      <span>联系邮箱：<a href="mailto:admin@example.com">admin@example.com</a></span>
+    </div>
+    <div class="contact-item">
+      <svg fill="none" stroke="currentColor" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M13 10V3L4 14h7v7l9-11h-7z"></path></svg>
+      <span>服务状态页：<a href="https://status.example.com" target="_blank" rel="noopener">status.example.com</a></span>
+    </div>
+  </div>
+  <div class="footer">
+    <svg class="brand-icon" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg">
+      <path d="M13 2L3 14H12L11 22L21 10H12L13 2Z" />
+    </svg>
+    <span>OpenFlare Protection</span>
+  </div>
+</div>
+</body>
+</html>
+`;
+
+export default html;