feat(mui): kit — DateField over MUI X (date-fns v4, cs locale) + LocalizationProvider

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

src/admin/ui/DateField.tsx

@@ -0,0 +1,37 @@
+import { DatePicker } from "@mui/x-date-pickers/DatePicker";
+import { parseISO, format, isValid } from "date-fns";
+
+/**
+ * Date input over MUI X DatePicker. String in / string out ("yyyy-MM-dd", or ""),
+ * so it drops into existing form state. cs locale + dd.MM.yyyy display are provided
+ * by the LocalizationProvider in MuiProvider.
+ */
+export default function DateField({
+  value,
+  onChange,
+  label,
+  disabled,
+  minDate,
+  maxDate,
+}: {
+  value: string;
+  onChange: (value: string) => void;
+  label?: string;
+  disabled?: boolean;
+  minDate?: Date;
+  maxDate?: Date;
+}) {
+  const parsed = value ? parseISO(value) : null;
+  return (
+    <DatePicker
+      label={label}
+      disabled={disabled}
+      minDate={minDate}
+      maxDate={maxDate}
+      value={parsed && isValid(parsed) ? parsed : null}
+      onChange={(d) => onChange(d && isValid(d) ? format(d, "yyyy-MM-dd") : "")}
+      format="dd.MM.yyyy"
+      slotProps={{ textField: { size: "small", fullWidth: true } }}
+    />
+  );
+}

src/admin/ui/index.ts

@@ -15,3 +15,4 @@ export { default as Alert } from "./Alert";
 export { Tabs, TabPanel } from "./Tabs";
 export type { TabDef } from "./Tabs";
 export { default as Pagination } from "./Pagination";
+export { default as DateField } from "./DateField";