feat(mui): kit — Select, StatusChip, CheckboxField, Alert

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/ui/Select.tsx

@@ -0,0 +1,42 @@
+import MuiTextField, { type TextFieldProps } from "@mui/material/TextField";
+import MenuItem from "@mui/material/MenuItem";
+
+export interface SelectOption {
+  value: string | number;
+  label: string;
+}
+
+type SelectProps = Omit<TextFieldProps, "onChange" | "select" | "value"> & {
+  value: string | number;
+  onChange: (value: string) => void;
+  options?: SelectOption[];
+};
+
+/** Dropdown styled like the kit TextField; composes inside <Field>. */
+export default function Select({
+  value,
+  onChange,
+  options,
+  children,
+  ...props
+}: SelectProps) {
+  return (
+    <MuiTextField
+      select
+      size="small"
+      variant="outlined"
+      fullWidth
+      value={value}
+      onChange={(e) => onChange(e.target.value)}
+      {...props}
+    >
+      {options
+        ? options.map((o) => (
+            <MenuItem key={o.value} value={o.value}>
+              {o.label}
+            </MenuItem>
+          ))
+        : children}
+    </MuiTextField>
+  );
+}