fix: 修复公告 API 路由顺序 — /today 和 /stats 在 /{id} 之前匹配

将具体路由移到参数化路由之前，避免 "today"/"stats" 被 {announcement_id} 作为整数解析而返回 422。

app/api/announcements.py

@@ -57,17 +57,6 @@ async def list_announcements(
     )
 
 
-@router.get("/announcements/{announcement_id}", response_model=AnnouncementResponse)
-async def get_announcement(announcement_id: int, db: AsyncSession = Depends(get_db)):
-    result = await db.execute(
-        select(Announcement).where(Announcement.id == announcement_id)
-    )
-    item = result.scalar_one_or_none()
-    if item is None:
-        raise HTTPException(status_code=404, detail="公告不存在")
-    return AnnouncementResponse.model_validate(item)
-
-
 @router.get("/announcements/today", response_model=AnnouncementListResponse)
 async def get_today_announcements(db: AsyncSession = Depends(get_db)):
     today = datetime.now().date()
@@ -106,3 +95,14 @@ async def get_stats(db: AsyncSession = Depends(get_db)):
         "new": new_count.scalar() or 0,
         "unsent": unsent.scalar() or 0,
     }
+
+
+@router.get("/announcements/{announcement_id}", response_model=AnnouncementResponse)
+async def get_announcement(announcement_id: int, db: AsyncSession = Depends(get_db)):
+    result = await db.execute(
+        select(Announcement).where(Announcement.id == announcement_id)
+    )
+    item = result.scalar_one_or_none()
+    if item is None:
+        raise HTTPException(status_code=404, detail="公告不存在")
+    return AnnouncementResponse.model_validate(item)