feat: 实现联系表单提交与邮件通知功能

添加联系表单提交接口和邮件通知功能，支持从环境变量读取 SMTP 配置
重构 SEO 配置到 site.json，新增 robots.txt 和 sitemap.xml 生成
更新公司电话并添加 PM2 生产运行配置

lib/contact-mailer.ts

@@ -0,0 +1,116 @@
+import nodemailer from "nodemailer"
+import type { ContactFormData } from "@/lib/contact-form"
+import type { ContactMailerConfig } from "@/lib/contact-mailer-config"
+
+type ContactNotificationMeta = {
+  submittedAt: string
+  sourceUrl: string
+  ipAddress: string
+  userAgent: string
+}
+
+function escapeHtml(value: string) {
+  return value
+    .replaceAll("&", "&")
+    .replaceAll("<", "&lt;")
+    .replaceAll(">", "&gt;")
+    .replaceAll("\"", "&quot;")
+    .replaceAll("'", "&#39;")
+}
+
+function formatOptionalField(value: string) {
+  return value || "未填写"
+}
+
+export async function sendContactNotification({
+  config,
+  payload,
+  meta,
+}: {
+  config: ContactMailerConfig
+  payload: ContactFormData
+  meta: ContactNotificationMeta
+}) {
+  const transporter = nodemailer.createTransport({
+    host: config.smtp.host,
+    port: config.smtp.port,
+    secure: config.smtp.secure,
+    auth: {
+      user: config.smtp.auth.user,
+      pass: config.smtp.auth.pass,
+    },
+  })
+
+  const subject = `${config.notification.subjectPrefix} - ${payload.company} / ${payload.name}`
+  const text = [
+    "官网获取初步方案表单有新提交。",
+    "",
+    `姓名：${payload.name}`,
+    `公司 / 品牌：${payload.company}`,
+    `电话：${payload.phone}`,
+    `门店规模：${formatOptionalField(payload.scale)}`,
+    `需求描述：${formatOptionalField(payload.message)}`,
+    "",
+    `提交时间：${meta.submittedAt}`,
+    `来源页面：${meta.sourceUrl}`,
+    `来源 IP：${meta.ipAddress}`,
+    `User-Agent：${meta.userAgent}`,
+  ].join("\n")
+
+  const html = `
+    <div style="font-family: Arial, sans-serif; color: #111827; line-height: 1.7;">
+      <h2 style="margin: 0 0 16px;">官网获取初步方案表单有新提交</h2>
+      <table style="border-collapse: collapse; width: 100%; max-width: 720px;">
+        <tbody>
+          <tr>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; width: 160px; background: #f9fafb;">姓名</td>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb;">${escapeHtml(payload.name)}</td>
+          </tr>
+          <tr>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; background: #f9fafb;">公司 / 品牌</td>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb;">${escapeHtml(payload.company)}</td>
+          </tr>
+          <tr>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; background: #f9fafb;">电话</td>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb;">${escapeHtml(payload.phone)}</td>
+          </tr>
+          <tr>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; background: #f9fafb;">门店规模</td>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb;">${escapeHtml(formatOptionalField(payload.scale))}</td>
+          </tr>
+          <tr>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; background: #f9fafb;">需求描述</td>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; white-space: pre-wrap;">${escapeHtml(formatOptionalField(payload.message))}</td>
+          </tr>
+          <tr>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; background: #f9fafb;">提交时间</td>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb;">${escapeHtml(meta.submittedAt)}</td>
+          </tr>
+          <tr>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; background: #f9fafb;">来源页面</td>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb;">${escapeHtml(meta.sourceUrl)}</td>
+          </tr>
+          <tr>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; background: #f9fafb;">来源 IP</td>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb;">${escapeHtml(meta.ipAddress)}</td>
+          </tr>
+          <tr>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb; background: #f9fafb;">User-Agent</td>
+            <td style="padding: 8px 12px; border: 1px solid #e5e7eb;">${escapeHtml(meta.userAgent)}</td>
+          </tr>
+        </tbody>
+      </table>
+    </div>
+  `
+
+  await transporter.sendMail({
+    from: {
+      name: config.smtp.from.name,
+      address: config.smtp.from.email,
+    },
+    to: config.notification.to,
+    subject,
+    text,
+    html,
+  })
+}