feat: Ernten und Chargen im Admin loeschbar machen

Neue deleteHarvestAction/deleteBatchAction, jeweils mit vorheriger
Referenzpruefung statt rohem Datenbankfehler: eine Ernte laesst sich nur
loeschen, wenn keine Chargen/Produkte mehr darauf verweisen, eine Charge
nur, wenn sie keinem Produkt zugeordnet ist und in keiner Bestellung
verwendet wurde (Chargen-Code steht auf Rechnungen/QR-Codes und darf aus
Nachweispflicht nie verschwinden). Loeschen-Button erscheint in den
Listen nur, wenn die Loeschung tatsaechlich moeglich ist, mit
Bestaetigungsdialog wie beim bestehenden Benutzer-Loeschen.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

src/app/admin/ernten/page.tsx

@@ -1,14 +1,20 @@
 import Link from "next/link";
 import { prisma } from "@/lib/prisma";
 import { BackLink } from "@/components/back-link";
+import { ConfirmForm } from "@/components/confirm-form";
 import { formatDate } from "@/lib/format";
-import { createHarvestAction, toggleHarvestPublishedAction, syncHarvestsFromApiCoreAction } from "../actions";
+import {
+  createHarvestAction,
+  toggleHarvestPublishedAction,
+  syncHarvestsFromApiCoreAction,
+  deleteHarvestAction,
+} from "../actions";
 import { getLocale } from "@/i18n/locale";
 import { getDictionary } from "@/i18n/get-dictionary";
 
 export default async function AdminHarvestsPage(props: PageProps<"/admin/ernten">) {
   const t = getDictionary(await getLocale());
-  const { synced, updated, skipped, failed, syncError, batchSynced, batchSkipped, batchFailed, batchLoadError } =
+  const { synced, updated, skipped, failed, syncError, batchSynced, batchSkipped, batchFailed, batchLoadError, error } =
     await props.searchParams;
   const harvests = await prisma.harvest.findMany({
     orderBy: [{ year: "desc" }, { harvestDate: "desc" }],
@@ -20,6 +26,9 @@ export default async function AdminHarvestsPage(props: PageProps<"/admin/ernten"
       <BackLink href="/admin" label={t.adminHarvestsPage.backToDashboard} />
       <h1 className="text-2xl text-forest mb-8">{t.adminHarvestsPage.title}</h1>
 
+      {error ? (
+        <p className="mb-6 text-sm text-red-700 bg-red-50 border border-red-200 px-4 py-3">{error}</p>
+      ) : null}
       {synced !== undefined ? (
         <p className="mb-6 text-sm text-forest bg-forest/5 border border-forest/20 px-4 py-3">
           {t.adminHarvestsPage.syncResult(Number(synced), Number(updated ?? 0), Number(skipped ?? 0), Number(failed ?? 0))}
@@ -82,10 +91,22 @@ export default async function AdminHarvestsPage(props: PageProps<"/admin/ernten"
                   <form action={toggleHarvestPublishedAction} className="inline">
                     <input type="hidden" name="id" value={harvest.id} />
                     {harvest.isPublished ? null : <input type="hidden" name="isPublished" value="on" />}
-                    <button type="submit" className="text-forest underline">
+                    <button type="submit" className="text-forest underline mr-4">
                       {harvest.isPublished ? t.adminHarvestsPage.unpublish : t.adminHarvestsPage.publish}
                     </button>
                   </form>
+                  {harvest._count.batches === 0 && harvest._count.products === 0 ? (
+                    <ConfirmForm
+                      action={deleteHarvestAction}
+                      confirmMessage={t.adminHarvestsPage.deleteConfirm(`${harvest.type} ${harvest.year}`)}
+                      className="inline"
+                    >
+                      <input type="hidden" name="id" value={harvest.id} />
+                      <button type="submit" className="text-red-700 underline">
+                        {t.adminHarvestsPage.delete}
+                      </button>
+                    </ConfirmForm>
+                  ) : null}
                 </td>
               </tr>
             ))}