Add Kiosk category to seed data, clean .gitignore

- Kiosk (🏪) added to fresh-install seed data in admin_server.py
- .gitignore now excludes .venv/, *.db, *.xlsx, admin.db

.gitignore

@@ -2,3 +2,8 @@ __pycache__/
 *.pyc
 assets.db
 uploads/
+.venv/
+*.db
+*.xlsx
+admin.db
+canteen_admin.db

admin_server.py

@@ -312,7 +312,8 @@ def _seed_data(conn: sqlite3.Connection):
     _seed_if_empty(conn, "categories", ("name", "icon"), [
         ("Bev", "🥤"), ("Snack", "🍿"),
         ("Food", "🍔"), ("Equipment", "🔧"),
-        ("Appliances", "🔌"), ("Other", "📦"),
+        ("Appliances", "🔌"), ("Kiosk", "🏪"),
+        ("Other", "📦"),
     ])
     _seed_if_empty(conn, "key_names", ("name",), [
         ("MK500",), ("Green Dot",), ("Red Key",), ("Blue Key",),