feat: move all remaining inline logic from routers to services (Tier 2)

backend/app/routers/notifications.py

@@ -10,16 +10,16 @@ POST   /notifications/read-all    — mark all as read
 
 import uuid
 
-from fastapi import APIRouter, Depends, HTTPException, Query, status
+from fastapi import APIRouter, Depends, Query
 from sqlalchemy.orm import Session
 
 from app.database import get_db
 from app.dependencies.auth import get_current_user
 from app.domain.unit_of_work import UnitOfWork
-from app.models.notification import Notification
 from app.models.user import User
 from app.schemas.notification import NotificationOut, UnreadCountOut
 from app.services.notification_service import (
+    list_notifications,
     mark_as_read,
     mark_all_as_read,
     get_unread_count,
@@ -34,22 +34,14 @@ router = APIRouter(prefix="/notifications", tags=["notifications"])
 
 
 @router.get("", response_model=list[NotificationOut])
-def list_notifications(
+def list_notifications_endpoint(
     offset: int = Query(0, ge=0),
     limit: int = Query(20, ge=1, le=100),
     db: Session = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
     """Return paginated notifications for the current user, newest first."""
-    notifs = (
-        db.query(Notification)
-        .filter(Notification.user_id == current_user.id)
-        .order_by(Notification.created_at.desc())
-        .offset(offset)
-        .limit(limit)
-        .all()
-    )
-    return notifs
+    return list_notifications(db, current_user.id, offset=offset, limit=limit)
 
 
 # ---------------------------------------------------------------------------
@@ -80,14 +72,8 @@ def read_notification(
 ):
     """Mark a single notification as read."""
     with UnitOfWork(db) as uow:
-        success = mark_as_read(db, notification_id, current_user.id)
-        if not success:
-            raise HTTPException(
-                status_code=status.HTTP_404_NOT_FOUND,
-                detail="Notification not found",
-            )
+        notif = mark_as_read(db, notification_id, current_user.id)
         uow.commit()
-    notif = db.query(Notification).filter(Notification.id == notification_id).first()
     return notif