feat(warehouse): add shared warehouse components

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/admin/components/warehouse/BatchPicker.tsx

@@ -0,0 +1,48 @@
+import { useQuery } from "@tanstack/react-query";
+import { jsonQuery } from "../../lib/apiAdapter";
+
+interface Batch {
+  id: number;
+  quantity: number;
+  unit_price: number;
+  received_at: string;
+  is_consumed: boolean;
+}
+
+interface BatchPickerProps {
+  itemId: number | null;
+  value: number | null;
+  onChange: (batchId: number, unitPrice: number) => void;
+}
+
+export default function BatchPicker({
+  itemId,
+  value,
+  onChange,
+}: BatchPickerProps) {
+  const { data: batches } = useQuery({
+    queryKey: ["warehouse", "batches", itemId],
+    queryFn: () =>
+      jsonQuery<Batch[]>(`/api/admin/warehouse/items/${itemId}/batches`),
+    enabled: !!itemId,
+  });
+  return (
+    <select
+      className="admin-form-select"
+      value={value ?? ""}
+      onChange={(e) => {
+        const batchId = Number(e.target.value);
+        const batch = batches?.find((b) => b.id === batchId);
+        if (batch) onChange(batch.id, Number(batch.unit_price));
+      }}
+    >
+      <option value="">-- auto FIFO --</option>
+      {batches?.map((b) => (
+        <option key={b.id} value={b.id}>
+          {new Date(b.received_at).toLocaleDateString("cs-CZ")} | {b.quantity}{" "}
+          ks | {Number(b.unit_price).toFixed(2)} Kč
+        </option>
+      ))}
+    </select>
+  );
+}