feat: 最新公告改为全来源最新6条按时间排序

去掉关键词过滤限制，两个来源的公告统一按 publish_date 倒序取6条。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/wechat/handler.py

@@ -243,27 +243,26 @@ class WeChatMessageHandler:
 
         try:
             async for db in get_db():
-                stmt = (
+                result = await db.execute(
                     select(Announcement)
-                    .where(Announcement.keyword_matched == True)  # noqa: E712
                     .order_by(desc(Announcement.publish_date))
-                    .limit(5)
+                    .limit(6)
                 )
-                result = await db.execute(stmt)
                 items = result.scalars().all()
 
                 if not items:
                     await self.client.send_text("暂无公告", from_user)
                     return None
 
-                lines = ["最新公告（最近5条）:"]
-                for i, ann in enumerate(items, 1):
-                    date_str = ann.publish_date.strftime("%m-%d %H:%M") if ann.publish_date else "?"
-                    title = ann.title[:28] + "..." if len(ann.title) > 28 else ann.title
-                    source = ann.source_name or ann.source_code
-                    lines.append(f"{i}. [{date_str}] {source}")
-                    lines.append(f"   {title}")
-                await self.client.send_text("\n".join(lines), from_user)
+                for ann in items:
+                    title = ann.title if len(ann.title) <= 128 else ann.title[:125] + "..."
+                    purchase_name = ann.purchase_name or ""
+                    if len(purchase_name) > 25:
+                        purchase_name = purchase_name[:22] + "..."
+                    time_str = ann.publish_date.strftime("%Y-%m-%d %H:%M") if ann.publish_date else "时间未知"
+                    source_name = ann.source_name or ann.source_code or ""
+                    description = f"{source_name} | {purchase_name} | {time_str}"
+                    await self.client.send_textcard(title, description, ann.content_url or "", from_user)
         except Exception as e:
             logger.error(f"查询最新公告失败: {e}")
             await self.client.send_text("查询失败，请稍后再试", from_user)