v1.4: group folder/photo limits and ad banners

Co-authored-by: Cursor <cursoragent@cursor.com>

app/banner_service.py

@@ -0,0 +1,16 @@
+from app.models import AdBanner
+
+
+def get_banners(position=None):
+    query = AdBanner.query.filter_by(is_active=True).order_by(AdBanner.sort_order, AdBanner.id)
+    if position:
+        query = query.filter_by(position=position)
+    return query.all()
+
+
+def get_banners_by_position():
+    banners = get_banners()
+    grouped = {}
+    for banner in banners:
+        grouped.setdefault(banner.position, []).append(banner)
+    return grouped