docs: 更新PROJECTS.md添加技术论坛项目记录

works/mailbox/inbox.json

@@ -0,0 +1,14 @@
+{
+  "description": "邮件收件箱状态追踪",
+  "last_check": null,
+  "emails": {
+    "1": {
+      "subject": "Fw: A股板块分析方案汇总",
+      "sender": "wlq@tphai.com",
+      "date": "Fri, 10 Apr 2026 16:38:39 +0800",
+      "status": "done",
+      "has_attachment": false,
+      "path": "/home/xian/.openclaw/workspace-coder/works/mailbox/emails/1"
+    }
+  }
+}