feat: CSV-Import/-Export für Gerichte/Allergene/Zusatzstoffe, RSS-Fix für mehrere Essenszeiten

CSV-Import/-Export (Gerichte, Allergene, Zusatzstoffe): neue Export-/
Import-Routen unter app/api/*/export und */import, hand-geschriebener
CSV-Parser/-Serializer (lib/csv.ts, keine neue Abhängigkeit), Upsert
über Kürzel (Allergene/Zusatzstoffe) bzw. exakten Namen (Gerichte,
mit Ambiguitäts-Check bei Namensdopplung). UI-Buttons in DishManager
und CodeListManager.

RSS-Feed: <content:encoded> zusätzlich zu <description> ausgeben,
da mehrere Feed-Reader description als kürzbare Vorschau behandeln
und dadurch bei mehreren Essenszeiten pro Tag nur die erste zeigten.

Version 1.7.0.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

components/CodeListManager.tsx

@@ -34,6 +34,8 @@ export default function CodeListManager({
     namePl: string;
   } | null>(null);
   const [error, setError] = useState<string | null>(null);
+  const [notice, setNotice] = useState<string | null>(null);
+  const [ioBusy, setIoBusy] = useState(false);
   const [translateState, setTranslateState] = useState<"idle" | "busy" | "done">(
     "idle"
   );
@@ -125,12 +127,77 @@ export default function CodeListManager({
     }
   }
 
+  async function exportItems() {
+    setError(null);
+    setNotice(null);
+    const res = await fetch(`/api/${table}/export`);
+    if (!res.ok) {
+      setError(formatMessage(dict.codeList.exportError, { message: String(res.status) }));
+      return;
+    }
+    const blob = await res.blob();
+    const url = URL.createObjectURL(blob);
+    const a = document.createElement("a");
+    a.href = url;
+    a.download = table === "allergens" ? "allergene.csv" : "zusatzstoffe.csv";
+    a.click();
+    URL.revokeObjectURL(url);
+  }
+
+  async function importItems(e: React.ChangeEvent<HTMLInputElement>) {
+    const file = e.target.files?.[0];
+    e.target.value = "";
+    if (!file) return;
+    setError(null);
+    setNotice(null);
+    setIoBusy(true);
+    const fd = new FormData();
+    fd.append("file", file);
+    const res = await fetch(`/api/${table}/import`, { method: "POST", body: fd });
+    setIoBusy(false);
+    if (!res.ok) {
+      setError(formatMessage(dict.codeList.importError, { message: String(res.status) }));
+      return;
+    }
+    const data = (await res.json()) as {
+      created: number;
+      updated: number;
+      skipped: { row: number; reason: string }[];
+    };
+    let msg = formatMessage(dict.codeList.importSuccess, {
+      created: data.created,
+      updated: data.updated,
+    });
+    if (data.skipped.length > 0) {
+      const reasons = data.skipped
+        .map((s) => formatMessage(dict.codeList.importSkippedRow, s))
+        .join("; ");
+      msg +=
+        " " + formatMessage(dict.codeList.importSkipped, { count: data.skipped.length, reasons });
+    }
+    setNotice(msg);
+    await load();
+  }
+
   return (
     <section className="card">
       <div className="flex items-center gap-3 mb-3">
         <h2 className="text-lg font-bold text-[var(--c-primary)] mr-auto">
           {title}
         </h2>
+        <button type="button" className="btn btn-neutral" onClick={exportItems}>
+          {dict.codeList.exportButton}
+        </button>
+        <label className="btn btn-neutral cursor-pointer">
+          {dict.codeList.importButton}
+          <input
+            type="file"
+            accept=".csv,text/csv"
+            className="hidden"
+            onChange={importItems}
+            disabled={ioBusy}
+          />
+        </label>
         <button
           type="button"
           className="btn btn-add"
@@ -148,6 +215,7 @@ export default function CodeListManager({
           {error}
         </p>
       )}
+      {notice && <p className="mb-2 text-sm text-green-700">{notice}</p>}
 
       {editing && (
         <form onSubmit={save} className="mb-3 space-y-2 border-b border-gray-200 pb-3">