add constraints on positive supercell construction

Author: Chiu Peter

crystal_toolkit/components/phonon.py

@@ -184,20 +184,23 @@ def _sub_layouts(self) -> dict[str, Component]:
                             default=1,
                             is_int=True,
                             label="x",
+                            min=1,
                             style={"width": "5rem"},
                         ),
                         self.get_numerical_input(
                             kwarg_label="scale-y",
                             default=1,
                             is_int=True,
                             label="y",
+                            min=1,
                             style={"width": "5rem"},
                         ),
                         self.get_numerical_input(
                             kwarg_label="scale-z",
                             default=1,
                             is_int=True,
                             label="z",
+                            min=1,
                             style={"width": "5rem"},
                         ),
                         html.Button(