feat: add message priority

Author: yoyo930021

src/github.ts

@@ -73,6 +73,9 @@ async function main() {
         channel: channel,
         text: "COSCUP 今天會議提醒：", // Add the requested prefix
         attachments: eventAttachments,
+        priority: {
+          priority: 'important',
+        },
       };
 
       await mattermostClient.sendMessage(combinedMessage);

src/utils/mattermost.ts

@@ -6,6 +6,9 @@ export interface MattermostMessage {
   attachments?: MattermostAttachment[]; // Add attachments property
   username?: string; // Keep other potential fields optional
   icon_url?: string;
+  priority?: {
+    priority: 'important' | 'urgent';
+  };
 }
 
 export class MattermostClient {