fix: ruff lint + format fixes in tests, ESLint fixes in frontend

backend/app/models/user.py

@@ -13,6 +13,7 @@ from app.database import Base
 
 class UserRole(str, enum.Enum):
     """User roles for RBAC."""
+
     admin = "admin"
     verkaeufer = "verkaeufer"
     buchhaltung = "buchhaltung"
@@ -29,13 +30,18 @@ class User(Base):
         default=uuid.uuid4,
     )
     email: Mapped[str] = mapped_column(
-        String(255), unique=True, nullable=False, index=True,
+        String(255),
+        unique=True,
+        nullable=False,
+        index=True,
     )
     password_hash: Mapped[str] = mapped_column(
-        String(255), nullable=False,
+        String(255),
+        nullable=False,
     )
     full_name: Mapped[str] = mapped_column(
-        String(200), nullable=False,
+        String(200),
+        nullable=False,
     )
     role: Mapped[UserRole] = mapped_column(
         Enum(UserRole, name="user_role"),
@@ -43,10 +49,14 @@ class User(Base):
         default=UserRole.verkaeufer,
     )
     language: Mapped[str] = mapped_column(
-        String(5), nullable=False, default="de",
+        String(5),
+        nullable=False,
+        default="de",
     )
     is_active: Mapped[bool] = mapped_column(
-        Boolean, nullable=False, default=True,
+        Boolean,
+        nullable=False,
+        default=True,
     )
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True),