feat: init slack messager

src/clients/slack.ts

+export async function sendSlackMessage(webhookUrl: string, params: {
+  issue: string,
+  displayName: string,
+  language: string,
+  siteEditor: string
+}) {
+  const text = [
+    `Issue: ${params.issue}`,
+    `Display Name: ${params.displayName}`,
+    `Language: ${params.language}`,
+    `Site editor: ${params.siteEditor}`
+  ].join('\n');
+
+  const res = await fetch(webhookUrl, {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({ text })
+  });
+
+  if (!res.ok) {
+    throw new Error(`Slack 推送失败: ${res.status} ${res.statusText}`);
+  }
+}
+
+// 示例用法
+// sendSlackMessage('https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX', {
+//   issue: 'Theme color missing',
+//   displayName: 'Lavender',
+//   language: 'en',
+//   siteEditor: 'https://www.strikingly.com/s/sites/12572142/edit'
+// }); 
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